I too like the Edelbrock 500 for a lot of reasons but the 390 Holley 4 bbl is popular as well on our inlines. The carb I would not use is the 390 Holley 2 bbl because the number is the same as their 4 bbl but it is all flowing through only 2 venturies where the 4 bbl runs about 1/2 that throught the primaries and won't allow all 390 cfm until the secondaries are also opened. To compensate for the large "holes" you will have to jet the 2 bbl richer and give it a larger accelerator pump shot than the same sized 4 bbl to keep the air fuel ratio near what makes the engine run correctly. This will end up having poorer gas mileage than if you ran the 4 bbl.
Flow rates for 2 bbl and 4 bbl carbs are not figured at the same vacuum readings so it gets more technical than what I just mentioned but the end result is still the same. The 4 bbl will end up being an all around better choice for a street driver.
Mike
