sorry if you get ofended but de dee deee don't spend over 3000 on a set of cnc heads and do any porting by hand or on any cnc heads for that reason if you want to really see if the valves need unshouding before you kill you combustion chamber send the to joe mondello have the wet flow tested and he'll tell you if you'll see any flow gain at all. theres no point in cutting the combustion chambers if they don't need cut are they cnc chambers if so don't worry about it just bolt them on either way you'll have to have them cc each chamber to be sure each cylinder has the same compression. i meantioned joe mondello don't get confussed with his site he doesn't just do oldsmobile he will work on anything but "BE WARNED" he is expensive but you'll never find a better porter in you life time if i had to pick between a set of cnc's from some other guy and a set of hand ported heads by him i'd take his hands down.