I have a 75 with the 390 with headers and comp. rv cam, edlebrock performer intake and holley 750 four barrel. this is a very nice set up, but if you don't at least have headers I've been told that a 650 is the biggest four barrel that you would want on your engine.
performer intakes work geat on every thing we have tried. If you dont have a carb. Try a Qjet(sounds sick I know)but they off road very well.they are 750cfm have vacum sec. air door only opens as much as motor can use. wont over carb. have used them on 215 buick alm. v8 to 514 ford! Get 75-80 has elc. choke but no computer. Can get tuning parts from edelbrock. from the montain. hillbilly
