390 w/open chamber heads

If I were back in Abilene, I could sell you a B body 8 3/4 housing...but I'm not.

Regardless of what gears you put out back, you also need to think about chassis and suspension upgrades-the power you will have would be utterly useless (with exception to roasting the goodyears) without traction. Subframe ties are very nearly a requirement for an A body