Very clean, nice.
So a late 70s head swap? Must’ve been desperate
Yeah that’s probably the clue. Earlier heads crack easy on freezing, but nothing else. I’m sure this heads are the generic open chamber 1.94s that everyone throws away

Are they BBC heads?
Man, we are going to have almost twin rigs! Your color looks almost exactly like mine, crazy that GM would offer 2 different colors that close in the same year. Just looked back at a couple of your first pics of it and my door panels are even weathered exactly the same as yours lol.
Should be very rewarding to get this project done. I've always thought it would be cool to do a build starting from a bare frame.

Seems like you need 3 cars worth of garage space to do this