How much horsepower can you expect to gain from a holley carb, good set of heads and a mild-med cam, if you keep stock manifolds? I dont what to spend the $ on headers approx. how much time would it take to do the swap? Can you just bolt parts on and call it a day or do you need to do a lot of tuning, im only familiar with FI engines. I'm just trying to decide if it is better to mod, do a engine swap,or just buy a new hull completely.

the square port heads on the 502 are pretty good, if you want to keep the price down go with the holley or demon carb with a nice alum. intake and cam. then add some performance exhaust manifolds. I used the eddie marine alum. manifolds with stainless risers on my old 29 baja and they picked it up almost 200 rpm