I've just come back from the machinist, I have good news and bad news, although I think it can go either way:
1. The head is in top shape, everything in spec, only the valves need to be lapped.
2. The cylinder walls don't look so good, especially the one that got stuck.
3. I'll need to overbore the cylinders.
So those are the main points, and being that the only piston kit I've found within reasonable price are the the ones from the 466 kit, that's the route I'm going, I talked to the machinist and he told me it can be done.
Since moving the frame inside I think I'll start doing a mock-up of the other parts and might do an electronics pan to get the new wiring done. Here's how it looks btw.