I have a 70 chevy c10 truck with a 3.08 gear, th400 trans, and a 4300 lb curb weight. I have 2 big blocks that I use. one is a 413 (bored 396) and a 468 (60 over 454).
I use the same cam and compression and exhaust system with both engines.
To me the 454 makes much better power under 3000 rpms and then they seem to make about the same after that. maybe the 454 makes a little more upper rpm power but not much more.
I think I would build a 496 for a car that big or add a turbo and efi to your current engine.
2 bolt or 4 bolt doesn't make a difference under 600 hp in a bbc.