Chris, work done on the body looks good! Agree with you that the total stripping, dipping, etc. is not really required - however you have done quite a thorough dismantling!
Regarding the engine, out of interest, what are you going to do:
Oil filter: keep the early one, which does not have a filter cartridge, or modify to take the later one?
Big end: Will you keep the white metal or convert to shells?
Oil pump: will you keep as is, or upgrade to later one for bigger flow?
Conrods: It was written elsewhere that conrods on early engines, especially 2 l B20, are a bit weak: new more solid ones, or reuse the existing ones?
As you are going to upgrade the heads to B12, and are looking for some more power from your B21 engine, above modifications could make sense!
We all look forward to a lot of engine photos....