you`re about to get 50 different responses from 50 different members .. i like having more carb than i need and not using it rather than having too little and wanting it .( goes with a few other things in life ) .. i run 750 vacuum sec, holleys on everything from my 289 all the way up to my 429 .. the engine will only draw in what it wants .. to a degree .. now you can slam too big a double pumper on stuff ..