Reviving the Dart Lite for daily driving...how should I spend the $$$?

You have tried to the best of your ability to remedy the carb problem:read2: I would find a carb guy and pay for some help.If you have replaced the needle & seat and gaskets and it's leakin & chokin then it;s time IMO:munky2:
Biggest struggle on carbs is age. Bodys have stripped holes, emulsion tubes break, acc pump linkage stick, etc. The carbs are so basic, I am comfortable I am re-assembling right, if I can find a good core.
Your car is an oddity. I'm surprised you could even get the 3 speed manuel, let alone the auto in a Feather Duster or Dart Light. The major part of getting the good gas milage was the overdrive 4 speed trans so those other trans defeated the purpose of the car.
In theory, all Dart Lite or Feather Dusters were supposed to get the 4 speed OD, mine was an early model that got out before the OD were mandated. It should be big bolt pattern and discs too, but has small bolt pattern and drums.
I'd say fix the carb problem, whatever that takes. MAYBE go to a super six setup. I'm not familiar with it, is it progressive? If so it would be good for mileage. I wonder about the future plan to use the OD trans with your current 2.94 gears. Result would be about 2.15. Curious as to how the slant would pull that on the highway. Would be interesting to see what kind of mileage numbers you could get. In town would be about the same as having the 3 speed you have now, just with an OD for the road.

Reports are the 2 bbl setup roughly = the 1 bbl setup for MPG, provided you drive nicely. You have more HP with the 2bbl setup. If I can find a 2bbl setup I can afford, I would go that way.
I imagine the ratios will be less than optimal, but my commute is either 55-65 or 25-30 on the highway. I figure that avoids the middle area where the ratios are no ideal?