Well I don't have a 331 but this still my help out. Its a 347. And it did pass emissions (here in Ca.), not even close to failure! heres the mods:
CHP 347, AFR 185's,10.5 to1 comp. , Cam with 523/541 212/222, Cobra intake, 30lb injectors, 255lph fuel pump, Areo fuel reg., motorsport short...