IF you are buying a new carb, stay on the smaller side. 350 to 600cfm. If you are running a stock 283 to 350 cu.in., you don't need a bigger carb. Too big you will loose your bottom end. Too small you will loose the top end. I would think you need the bottom end more on a stock motor for pulling and everyday driving. Holley makes a 570 Avenger that is more than enough for stock with an RV cam. An edelbrock is a fairly cheap and GOOD carb. Just keep it small. Don't let the parts guy tell you different. You will suck a lot of gas and loose the performance you need and want if you go too big.
