Marine once you get those heads back you won't take time out to be polishing any ports, they'll look so good all you'll be wanting to do is get them back on the block and out on the track. I once had a set of 428 CJ heads, (got'em from the Ford dealership back when Ford Motor Company supported HP), Ford had done the porting and polishing work, also did the valve seats, talk about instant bolt on power...great investment. hooah