I'm running the same stroker as you with a 4.15 stroke using closed chamber Indy EZ heads but I had the bowls opened up to 85cc. Flat top pistons .007" in the hole. .040" MLS head gasket. 38 degrees locked timing. Compression is 10.9 to 1 and .047" quench and it makes 750hp on pump gas. I would listen to these guys when they say to lower the head down and open the chamber up some and you will make more power and should not detonate.
