The difference?
Slightly less acceleration and slightly more mileage.
That’s it. If you cruise the car, you’ll like the 2.76 better.
I had that ratio, the 2.76, in my ‘79 Magnum w/a 360/904 on 26” tires and I was able to get up to 20 mpg’s. No headers, dual exhaust off of the exhaust manifolds...