Guy I know wants to get a little more out of his 73 318 with 675 heads. Wondering if 302s are less ccs in order to bump compression up a little, or is planing the 675s, or magnums a better choise? Will allso be adding a 4bbl, headers, and an RV type cam. Anyone done this? How much of a gain would it accomplish? The vehicle it is in only weighs 1800lbs
