Edelbrock heads.

That the better heat conductivity and thus cooler surfaces of AL heads reduce the tendency for pinging/detonation. He got rid of his pinging with AL heads despite going to higher CR and advancing timing too...higher CR and advanced timing tend to increase the tendency to detonate.

Oh wait, I see. When you say 'helps' you mean 'reduces'; I thought you meant 'increases'..... I was really confused LOL. The coffee has not kicked in yet!

I don't think I would discount a better combustion chamber shape rather that the material the head is made from.