500-600cfm 4brl. carb wanted

I am in need of a 500-600 cfm 4brl carb for my 318la with performer intake. The carb that is on it now is way too big and has no choke. Does anyone have a new, newer, or rebuilt one that i can just bolt on? i don't want anything has to be rebuilt or isn't running right....lemme know what u got, thanks.