My old 420 cubic inch W9 motor heads were ported by modern cylinder heads heads flowed 387@750 14.5 compression 280-288 roller with 430-440 lobe Jesel rockers 1.8 intake 1.85 exhaust 420 intake ported by Ryan apd 1150 carb ran a best of 9.33 @147 with a lazy 1.42 60 ft motor differently had a 8 sec pass in it sold everything and bought a R5 P7 motor