One of the first motors I built for a customer a long time ago was a 383 with the stock early 4 bolt valve cover heads(little valves and all ) and a early production Eddy two piece STR (Street Tunnel Ram maybe)crossram intake manifold, it had either 600 or 650 Holley D.P. on it, CRS It ran well above 3000 RPM but most of that was due to the cam and a stone stock low stall OEM conveter I've since owned and race a bunch of BB with M.W. heads and crossrams with dual carbs, all the way from stock to using dual Holley 850 D.P., as already suggested get a set of Holley 650 or 750 D.P. or a set of the Hi Po(non smog carbs) Eddy or Carter type (625 or 750 CFM)carbs will work good also Mopar BB like a lot of air and fuel is what I have seen in testing and racing