It all depends on what power you are looking for. The World S/R heads will have a more modern port than any factory head. Do you have some 441 GM castings laying around that you can use? If not, buy the time you buy a used set, bring them up to snuff with re-conditioning, you will have almost as much invested as new heads. If you go for any kind of porting you will be equal to or over what new heads will cost. I would look for a used set of Vortecs (modern ports and chambers) and put the beehive valve springs to they don't need to be machined to accommodate high valve lift. You would need a vortec manifold though. What I would really do is invest in new Dart S/S heads or Iron Eagle 180 heads. Modern ports and chambers. I believe you can get them complete on E-bay for about 600-700 bucks.