how much horsepower from my 318?

Find one of those warehouse brand cams, that are like 260/270 adv duration, with like 420-440 lift. easy on an old engine, but yet gives a bit more power. The Comp or ISKY 260/260 cams are my favorite for a cam/manifold/carb uprade for a 318. The valve guide seals will need replacing a few hundred miles after the cam change though. No big deal.