I would hardly call choosing a carb.(a black art).Choosing the right carb is the simple formula of CID X MAX. RPMS DIVIDED BY 3456.After that you would have to figure out your volumetric efficiency of your engine.Most street engines are around 80-85 % efficient.Go to www.Holley .com and then click on Tech. library.When you look at this chart and read what they say you will see that a stock 350 does not need 750 cfm.After all an engine only needs so much air.