68 truck 318 cam. How big can i go?

If you mill so much off the heads, then you have to get the intake milled to compensate for proper fit. Then you have to keep those heads and intake together and can't interchange them on other engines.

Just something to keep in mind.... #-o

I think I'll just have the intake side of the heads milled so any 318 intake will work. Seems more logical than milling the intake.