318 2bbl to 4bbl: Is it worth it this time?

My 75 Dart with dual exhaust (2.25" piping) and turbo mufflers currently has a decent 2bbl on it and runs well. It averages between 13-14.5 mpg total for a full tank with 3.21 gears and mixed driving.

I have done many 4 bbl swaps, but is stepping up to a 4bbl this time worth it and will it help milage? It is just a travel to work 40 miles a day ride, not a drag car. If four barrel, I was thinking manual choke 500 cfm Eddie and ubiquious 2176 performer intake.