Not real sure what everyone else said but if I were you I would run a 600 or 650 first off. Then it all depends on the carb and what you want out of it. I have always heard and have tried both that Holley is more of a strip kind of carb. They are good carbs for better power. Need more tuning but good. Edelbrock are good for plain street motors and stay in tune well. Edelbrocks aren't good IMO for strip or major power, they seem to just be plain street carbs and better on gas milage. If I would have known this earlier before I bought my Edelbrock then I would have gotten a Holley. I am not too happy with power gains from the Edelbrock carb I have. Didn't add no power and actually my 2 barrell seemed to pick up much better and a more snappy throttle response.