360view,
Thanks for that excellent info. It seems everyone has a "rule" for aluminum heads from "you must raise compression" or they "drop compression".
In the end, when I bought the Edelbrocks for my 408 stroker I came to the conslusion that compression ratio stays the same (built mine for 10:1 nice and safe on pump gas) but you can run a higher compression ratio before you start to see negative effects with the aluminum heads.

Scott