Fine work.

Check it out, I got the cylinder block back from SRM!

The parcel arrived ages ago, but I've only been able to get to it now, so in fairness it took them no time at all to send it back to me.
Something else worth noting (I should have taken photos as I opened it, sorry!) is that it was all packaged really, really well: plenty of shockproof chips and bubblewrap, reinforced tape everywhere, cardboard "plates" around the cylinders, etc.
There are also the pistons, rings and cam followers.

So, what was all this for? The boys gapped the rings for me, and honed the bores for the correct clearance (0.005").
They also honed the cam follower tunnels so now everything fits as it should. The more keen-eyed will have noticed that the four retaining bolts are not safety-wired, don't worry, I'll get that done properly.
This is a close-up of one of the bores, where you should be able to see the plateau honed finish (don't worry about what looks like imperfections, those are actually just WD-40 bubbles).

And this is a (blurry) close-up of the oil return passage, behind the number 2 cylinder: no witchcraft here, it's just a tunnel, but you must make sure it is perfectly clean, free of anything that might obstruct oil, and that it lines up with the corresponding passages in the head and crankcase.

It all looks and feels really good, and really clean. The peace of mind of knowing the job has been done right will be something I'll always enjoy when riding.
That way I can be confident with the throttle, instead of worrying about how close I might be to catastrophic engine failure.

Well worth the short wait and highly recommended to anyone looking for a proper engineering shop.