i jsut bought these

open chamber 318 heads are around 68cc's, the 360 heads are a round 72cc's.

I would mill 8cc's off of them to end up at 64cc, but measure the chambers on the 360 head first.

every .0048 milled knocks off 1cc, so just mill them .040 and also mill .040 from the intake side of the heads as well, that or only mill .025 from the intake side and then just use the thinner felpro .035 replacement intake gasket.

jmo