Best BB bang for your buck?

For that kinda cheap I would go with a 383. They are overlooked, underrated and foggotten. 440s are a tight fit. REAL tight. the low deck motora fit a lot better and open up more possibilities for exhaust. The 400, though more cubes, will require literally .100" milled off the heads to get compression barely in the 9.1 range. Then, you gotta mill the intake a bunch, worry about adjustable rockers cause now the pushrods are too long....blah blah. Find a 383 and build it. You can get decent compression with stock heads and pistons and make plenty enough power to make an a body scoot. I gotta few things for a 383 if you're interested. they are just takin up space here.