I have a 88 convertible that is running 10lbs. of boost on a 306 with 4.10s 5 speed aluminun driveshaft, 42injectors, msd and 90 mass air with cobra intake and 70 throttle body. It is running stock heads and has a blown head gasket. Thought I might put a set of heads on it when I tear it down. What size runners do you think would do best and size of valves. Thanks for reply, Ben