So, a bit of an update from yesterday...
Sloth came up to have a look with me, and after the normal chat, leaning over the engine bay looking at it and going 'yep, it's F**KED', and probably a few bits of banter back and forth about sat nav units... we cracked on.
I'd got the heater box back in, with a new heater core (still Audi style - but a Nissens one this time, with bigger hose connections - 19mm instead of 16mm, so got rid of some excess joins in the pipe reducers) and tidyed/re-taped up the majority of the fascia looms, so we started off with plumbing in the new heater core into the engine bay, before briefly and gingerly turning it over a couple of times and starting it up (no belt or anything yet - literally for a few seconds to see if there were any horrible noises which might indicate us tearing it down!). Satisfied that it wasn't on the brink of self destructions, we headed off to the workshop to collect the replacement (old) PS pump, and a few other bits.
Getting back, we swapped the PS pump - (the design of the pulley on the one that destroyed itself was a bit different - so no idea if that made a difference), put the new belt on and filled it up with coolant.
Started up again and set to work bleeding the air out, which between getting it up to temperature and letting it cool a couple of times we investigated his random ABS Fault and brake lamp failure messages which were randomly popping up on the dash. After a bit of detective work with the Nanocom, we found the brake switch acting up, so pulled that apart and repaired it.
Back to my RR and another burping session, along with coolant sniff test, which came back negative. Another break for it to cool, followed by topping off the reservoir and then running it up to temp with the cap on and allowing it to build pressure this time. The good news is that the cooling system didn't seem to overpressurise, so things seem to be OK on that side of things.
The bad news... to me, although the engine still seems to run quite smooth and sweetly, there is a bit of a noise there, which I don't recall it being there before, and neither of us can put our finger on what it might be. Again, it doesn't seem to be blowing pressure into the crank case, so it might be either an exhaust gasket or head gasket blow to the outside? It's not so prominent that it's possible to pinpoint exactly where it's coming from either.
The other downside, is my MOT ran out on the 15th - it was booked in to be done on the 12th, but then this happened on the 9th, so it's had to be put off. So I can't really take the RR out for anything of a run to see how it performs under load and driving conditions - unless its being driven to a pre-arranged MOT. And I don't really want to book it in for the MOT, until I'm happy that it can do the required engine running bits without any signs of blowing/damage. So feel a bit between a rock and a hard place!
I have to finish getting the interior put back together - BECM back in properly, and the dash back together/ductwork in/instrument cluster etc before it's driveable anyway. I might then chance driving it around the estate/down to the local Tesco and back a few times to see how it performs. If it seems to be OK, and nothing presents itself, and that helps clear the last bit of the air out of the cooling system, then I might put it in for the MOT next week and see what presents itself. That way, if something does crop up, and it's got an MOT, then at least I can limp it up to the workshop, where it's easier to completely strip things down.
Part of me wasn't 100% happy with the heads when I got them back from the machine shop when I built the engine in the first place, so I have retrieved the heads from my old engine that came out (and hadn't had overheating issues) so I might look at slowly rebuilding those, and then doing a head gasket swap at some point for my own piece of mind.
But I guess the main thing out of it all is that nothing is springing out at us that says it needs an immediate teardown, so I think I have been pretty lucky. The biggest casualties out of this have been 1) my foot, 2) the old heater core 3) the nav unit - white screen and nothing happening 4) the HEVAC main board (fair few traces of coolant on it and in the connectors) and 5)the underside of the dash - it's got some surface scarring from being blasted with hot coolant/steam! but not noticeable from the outside luckily.
I've got a few more pictures of progress, which I'll put up once I've got them off my phone and onto the server.