That is a very open ended question that will be hard to respond to without more information/constraints. Are you talking Normaly Aspirated pump gas with no power adders, or race gas or other fuel, and are you using some sort of power adder? You sat this is for a '70 GTX, but is it a street car or race car? How much does it weigh? what suspension, tires, gears, transmission, converter, etc are you using?
