I'm running the rpm heads but they've been worked over by Ryan at shady dell.With the flat top pistons, my comp ratio is 11.2/1 which seems like a lot ,but with the aluminum heads I can still run a GOOD high test pump gas with no detonaton problems.
Buddy of mine up here in maine has a shady dell roller, stage 3 eddy headed 550 HP 408 in his plumb crazy 70 duster. A ride in that car was my inspiration to build a 408.