Help on 408 build

It would still need a cam change with AL heads. The 65 cc chambers are the maximum chamber size that I know of in typical SBM heads (Promaxx, Edelbrock, SpeedPro) and so the DCR with his cam and present pistons would still be well above 9 and that is still too high. At least he would get closed chambers and quench which would help, but he would still need to get the DCR in the mid 8's or lower at most to make an easy tune and get some margin. That would drive to bigger cam, which may or may not suit his intended engine use.

If you ran 9's, then you had a quite big duration cam, and that lowered the DCR to probably the low 8's or less, which put it in a safe zone for pump premium.