I got a 1975 Ford F-100 with 1971 Ford 460. It has a edelbrock torker II manifold and a Holley 3310 780 cfm carburetor,headers, C6 auto and a electonic ignition and is converted to unlead fuel, 2wd. The gas mileage is horrible. I want to change out the holley with something else. I have seen that this Holley can be upgraded by installing a ProForm carburetor main body, the Proform 67101C. Is this the way to go or do you have any better suggestions