Max horsepower with EQ heads?
Wouldah, couldah, shouldah.............Hummm. You think there is enough cross sectional area to take 408" to 7,200 rpm and make any power with the EQ heads? I stretched it to my limit to get 629 HP from the LAX heads with standard off-set rockers at 6,300 rpm.
Somebody build it. Let's see, huh? You bet I would try it. No guarantees though. Send me $10,000 to start the heads.
I think you would need to solid plug the pushrod holes, offset drill the plugs, cut out the pinch entirely, cut the stud mount bosses shorter and grind out the boss material completely from the port inside. Then design a shaft rocker system mount, for offset rockers, with what you have remaining of the stud boss threads.
Or buy a Victor heads because it would be cheaper.