Need some head, help

Well good question, the added air will fill more and thwt can add to squeeze...but yes I know the 360 head could be 72cc compared to the 68 cc 318 head. I think in a case like that, milling from 72 to 68 cc's wouldn't be too much hassle. But that's jmo and like mentioned, he might not want to deal with a head swap.