If you run an A500 OD with 2.76 gears,you're gonna have to drive about 95-100 mph to keep the motor in the sweet spot! 3.23 gears are about the bottom of the barrel to run with an OD tranny. I plan on trying an A999 lockup tranny with 2.45 rear gears in my wifes 69 Dart conv. The A999 will have the low first gear.I'd be interested to read what some of the good engine builders here have to say about what to do to a 273 to make it get good gas mileage.
3.23 gears are about the bottom of the barrel to run with an OD tranny. I plan on trying an A999 lockup tranny with 2.45 rear gears in my wifes 69 Dart conv. The A999 will have the low first gear.I'd be interested to read what some of the good engine builders here have to say about what to do to a 273 to make it get good gas mileage. 
