big block b headers in a body?

Iam building a duster with a 383 727 auto 83\4 rear with 456 gears.The motor has a purple shaft cam 915 heads and a eddy intake.I have 650holley double pumper but i think i need a 750 double. I am basicaly trying to put a decent street car on a tight budget and i dont even know the specs of the cam or the intake.I just the got the tranny rebuilt with a stage two transgo shift kit and a tci 3000 stall converter and now i am saving for headers.This car will be no show car .