Common problem with fat fendered cars. Correct timing port might help a little, and Jet Hot (or similar) coating on the headers will help some but as 34-40 and others have mentioned you have got to get some ventilation under the hood!!! Can't get much air in there and then it has no place to exit the hot air! Louvers on the inner panels will help a lot, along with some sore of air pickup under the car at the front to get some air coming into the underhood area....