FWIW, this car has 3.06 rear gears and a Tremec 5 speed with a .68 overdrive.

http://smg.photobucket.com/albums/v228/Avette4me/video/?action=view&current=20091126133941.mp4

Never had a problem using 5th, even with the high rear end ratio. I’m at ~2050 at 70 MPH and ~2350 at 80. Gave it a gas mileage check driving a full tank at 80 on the interstate and got about 17.9 on that run. It was always about 11 before the swap.

Your 2.73 might be a little high, but since it’s in already you can swap it later if needed.

The big picture
1958 Chevrolet Stepside in the Gallery
Photobucket album