The heads will depend on your price range. You're gonna have to make a phone call and talk with a techy to make sure you get the correct ones for your build. But somethin along the lines of 195cc int runner, 2.02/1.60 valves. They should have a .600" lift max, which is where the techy comes in, there's ALOT invovled in choosing heads.

A good place to start is the GM Vortech Heads, the only thing is you'll need a diff intake to match these heads.