Power levels , tires, Block Type/size, head size length width height and fit Intake/exhaust will eventually dictate classes..restricted by turbo, Example 3.0 SB makes 1200-1400HP , 3.6 1600-1800HP, SS on 460CI 2300HP+ .Why are even discussing head type if its factory Size width, height, and fits factory accessories. Yes there Are advantages to (Big bud) heads at certain volume rates but 3.6,3.0 are Not, Factory spec's will produce the HP the turbo creates.
Why should costs or options dictate the rules, If a guy wants to spend $10K on D-Max/Cummins/Ford heads(s)and someone other owners are running X at $4K and working that's call freedom of choice. I here this form time to time its to costly, So I sell you 1 set of heads/head once every 10 years, that's too costly. Outside of freshening them up after XX+ hooks run. I need to stay in business for those next 10 years for Ya.