I have just worked the ports and runners over and shaved these y303 heads combustion chambers down to 55 cc's, those are Proform 1.7:1 pedestal mount rockers which fit under the short cast aluminum valve covers after you remove the baffles and machine the mounting bosses flush. Craig Blood of Blood Enterprises in Auburn Washington is my chief technical advisor, parts supplier and machinist for the shaving and valve cutting, i cannot recommend he and his crew highly enough! If you want the best quality and no BS he is your man.
