you can do like a stage one port for about 1200 dollars and you should see like 20 HP.. if you put a cam in with it 45 HP.. mine is going in soon cost me 1800 for the heads and 200 to take the heads off and put back on.. but im getting hooked up..
I would highly reccomend adding a good set of cams, because your going to have to take everything apart, and there will be no additional labor for you.