L98 heads cam mod list ?

Hi i have a 1985 corvette bone stock l98 700r4 transmission. I am wondering if i should stick with simple bolt ons mainly air flow stuff bigger tb cold air intake headers true dual exhaust into high flow mufflers no cats or would heads and caming it do wonders the thing is i would like to get around 300-350 HP while keeping best gas milage possible (obviously) so has anyone done any simple mods on a stock l98 and gotten even close to that? and if heads and cam are the best bet what would you suggest and how much should i expect my MPG to drop with a cam? thanks so much i am just getting into cars and i know numbers and specs but i dont know much about heads and camming cars thanks again!