Some next level stuff...

Are you guys ready for this? I don't think you're ready for this. This is just beyond.

Ancillaries.

What, you thought that was it? There's plenty of stuff left that needs to go back onto the bike.
I'll start with the coil mounting bracket so I can get all that messy wiring out of the way. The Boyer module is tucked away above, and rubber mounted, in a manner of speaking.

Onto the head steady:

And now for the carburetters. First, the bakelite insulators, then the carb/manifold assemblies (it's slightly less of a pain in the ass fitting the manifolds to the carbs first, rather than to the head and then trying to fit the carbs.): anyone who's done this before on a Commando knows that this is another one of those things that require a truly zen state of mind, detached from worldly concerns, a steady rock, unwavering in the face of waves of frustration. Also, a ball-end allen wrench is really useful, I'm pointing to it in one of the photos below:

Don't forget the balance pipe!

The manifolds are a little bit special, because they are already tapered from 32mm for the carburetters to 30mm for the head. The carburetters themselves are pretty special in that they have the supposedly improved StayUp floats, and the rather nifty brass adjuster screws: it looks like I got the brass screws just in time as they are no longer available.

Fitting the K&N filter is much easier than the original type. I think this looks great on the Norton, shame it's hidden by the side panels on a Fastback, but on a Roadster with its smaller side panels, it really does look cool.

And onto the exhausts! I'm using a very small amount of copper grease on the lockrings since I don't like the idea of dry threads here.

Refitting the cylinder head.

Ok, now that the head gasket is ready, the head gets the last few things done and is then ready to go back on.
The little stack of rocker spindle cover plates and gaskets goes back on:

Word of caution: you should really leave the cover plates at the back (intake) off until you torque down the head, as they can interfere with the socket/wrench when bolting down the head onto the cylinder block, i.e. there ain't a lot of room there.

There were still two studs that needed to go on the cylinder block:

Something else I forgot to mention was that I tightened the four long through-bolts with a torque wrench. On a standard 850 barrel, I think there are washers there, and I had even got some when I ordered the last few things from Andover. However, they didn't fit in the Maney cylinder. Sure enough, they're not needed, as long as some oil is applied under the bolt head and on the threads, which is good practice anyway. It's important to not use too much oil, which especially in a blind hole could end up with nowhere to go and negate the correct tightness, despite an apparently correct torque reading. It's never really straightforward is it?!

and for my next trick, holding all pushrods into the head. You could do this with some rubber bands or zip ties ... or get a mate to help you. I preferred doing this by myself just so I could concentrate and take my time. It really isn't difficult, it just takes a little bit of care and a steady hand.

The maneuver to refit the head will seem counterintuitive, but the way described in the workshop manual is the way to do it. It's the reverse of how you take the head off, so you start with the head tilted at a 90° angle behind the cylinder block, pushrods facing forwards. Then you tilt the head forward until you locate the studs, and the pushrods are close to their tunnels.  There isn't a whole lot of room, and it's very important not to nick or bend the pushrods. Once you've cleared the cylinder block, you can free the pushrods, which should find their place on top of the cam followers, and lower the head. At this point the studs prevent the head from moving around and you can focus on locating the pushrod cups on the rocker ends. Again, this needn't be a fiddly, frustrating, maddening task: use a powerful light to look through each exhaust valve housing and guide the pushrods home with a thin screwdriver: it took me two minutes to do them all. Once you've got them, here's a neat trick to avoid having to start over:

The rubber bands keep the rockers firmly into the pushrods' cups.

Alright! It's starting to look like an engine again...

The more keen-eyed amongst you will have noticed two things: I removed the valve adjusters (although this wasn't strictly necessary to be honest), and I removed the front Isolastic mounting bolt, then "dropped" the engine as far forward as it would go.

This gave me more clearance up at the top to refit the head. Sorry I don't have any photos of the maneuver itself buy I was more concerned with not cocking it up than documenting it. Bottom line, there is absolutely no need and no reason to pull the engine out of the frame (with all the complication and extra time and labour to remove and refit the primary, clutch, etc.) "just" to do a top-end job. All in all, I would rate this an easy-to-medium difficulty task, and I'm no mechanic.
It's now time to go around the all important tightening sequence.

I decided to go with Champion sparking plugs this time:

Gasket time...

When I took the "modified" head off my engine, I thought I would re-use the head gasket that had been fitted. After all, that's the advantage of a solid copper gasket, you just anneal it and you're good to go.
That said, the old copper gasket had evidently gotten a little mangled around the pushrod tunnels (by no means unheard of, and not really a problem) and there was something else to consider: the new head had visibly less meat on the mating surface (although the step in the combustion chamber measured the correct .120") and as you know I've had it skimmed to ensure a truly flat surface for a proper seal. So, what we have here is a thicker solid copper gasket made by Jim Schmidt, specifically the 0.62" item.

The extra thickness is to compensate for the thin mating flange and its subsequent skimming. Additionally, it should allow adequate clearance for the heat insulating washers I've fitted under the intake valves and possibly lower the compression ratio slightly, though to be sure of that I would have to test it once the engine is back together and fully torqued down. Incidentally, jabbing your pinkie in the spark plug hole is not an accurate compression test. Get a gauge and measure properly.
Word of warning: it should be noted that the topic of head gaskets is one of those technical topics (like "which engine oil?") that inflames the Norton world, so don't be surprised if you can't find a definitive answer.
The first thing to do is anneal the gasket: after it's heated to a dull red, I leave it to cool on the bench and get on with the rest. Apologies for the rather cryptic image but I was by myself in the dark, and nothing good ever happens when it's like that:

This gasket came with some very thin copper wire, I've never tried this before but the idea is that it will provide a seal against the typical oil seepage that most Commandos experience around the pushrod tunnels and oil return hole. I start by applying a thin layer of sealant on the underside of the cylinder head, then lay down the wire in a loop, again apologies for the crappy photo:

The gasket, now cool, also gets an even layer of sealant on both sides, and then goes onto the cylinder.
We're finally ready for the head to go back on now.

The devil is in the details.

I'm at the stage where I'm ready to refit the cylinder head, bolt everything back on (carbs, head-steady, etc.) and see if the engine will work. BUT, before I can do that, I need to go over a few bolts with a torque wrench, and to do that, I needed a 5/16 insert. And finding anything non-metric, in a backwards metric village like Rome means your fun grinds to a disappointing halt real fast. "Special order" this, "not available that..." so disappointing. Unexpectedly though, I found just what I was looking for at a small hardware store operated by a bunch of young guys who wrench on their own dirt bikes and help each other out. Definitely an interesting find, and I'll be happy to support a local independent shop in the future.