Carb upgrade on 65 dart 2bbl 273

IMO, choose the edelbrock 500cfm and just the regular performer manifold. you will get better gas mileage when putting around town on just the primaries, but can open it up a bit for some pep. my 64 dart gt 273/2bbl 4speed had a 68 340 4bbl manifold and a 68 avs and it picked up a bit for a stock 2 bbl motor. and yes, dual exhaust will help it breath better. more coming in means more has to go out.