Carb upgrade on 65 dart 2bbl 273

Good luck with the project. The intakes aren't at your local store and make it hard sometimes. I've only seen one hanging on a wall at a speed shop once. Never bolted on. Engine owner purchase mistake. Sat for years.

On the carb, a 500 cfm 4bbl is what I also agree with. Though I do believe you'll find better mileage because the 2 bbl is rated differently than the 4bbl. 1/2 of the carb is what you'll be driving on.
Tune the primarys well and it'll be sweet. IMO, I'd do an electric choke.