I have used the 390 holley, but a double pumper version intended for competion use. Had to change jets, had a 290' Isky cam, 10/1 comp ratio, headders. Used the 6.5 power valve, but do not remember the jet sizes. The carb was very good in power, but fuel economy was not all that great. Had a lot of time trying a bunch of jet sizes till found the right one.