Better yet, buy the 505/502 short blocks, have someone tear down and machin (blueprint) properly (factory sucks) balance. Buy good marine set up Aluminum heads, good push rods and rockers, Dart manifold, 850 holley, better cam, MKSD dist/ignition good high volume oil pan and have a couple of 580-600 HP reliable motors. Money well spent IMHO, worked for me.