Good question and I'm sorry its one I can't answer. His old build was around 11.2-1 (flat-tops) but on this build he has my BEST set of Edelbrock heads and they are the piss-poor open chamber 340 style head. I know they would easily work with pump gas. I did this set for a Friend and when he decided to sell I bought them back because of the man hours I had in them. I can't wait to see how the closed chamber set work out but I probably won't get to try them for awhile so there's no rush to finish them.