sgtdel, is that quadrajet on your 383 just a stock replacement? I dont have quite the motor you do but Im trying to decide if a holley 600 is going to be plenty big for my motor. Its a 350, 4 bolt main bored .040 over, comp 270h cam, stock vortec heads, gm performance dual plane intake, long tube headers and 2.5 inch dual exhaust.