which heads for a 408ci?

but where can I buy econo w2s. I have looked on summit but they just have standard w2s. Also it would be alot more work need special intake rockers and headers. Which I don't really want to do. What is the max cfm any one ever got of a 596 head or j head. If I could port my head to support 500hp with comp XR274R solid roller cam than I would. Will see what I can get out of this 318 head.

A kid In my class said he got 244cfm out of 993 chevy head with a bowl blend and some work on the short side radius. it flowed like 200cfm stock and now with just a little work its up with edelbrock capabiltites. I don't beleive a word this kid says.