I totally get where you’re coming from....... but you have a Megablock, right? Anytime there’s a MP part involved......... it always suspect imo. I’m thinking....... head? Block?........ that’s a “pick em”.
I doubt it’s the gasket....... but you might luck out.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads