ok i have a stock 86 5.0 and its got 30,000 mi. on it. i was wonding if i put gt40 heads on it from a expolorer and the intake manifold on there and some sork of cam, roller rockers and all that ****. would i be close to getting 300 horse and i am putting 3.73s in it this winter i know i need mass air but what do you guys think it will do what year did the heads not need the special headers. and does anyone know about the piston to valve clearence.. thanks