Dont waste your time on the heads...just get rid of them and get a good set of GM heads....look for 049's or 781's with larger chambers...or 290's or 215's if you want smaller chambers, like with flat top pistons. The peanut port heads have smaller runners all the way thru, you cant die grind out the whole port. Also, if the headers are too big of a diameter, that's no good either. No bigger than 2" for what you want.