What gears with OD A-833?

I was able to look at a trans, rear axle calculator that was on bigblockdart.com

I calculated my A833 O/D setup. In O/D gear, with 27" tall tires and 3.73 gears at 73.7 mph the engine will be turning happily at 2500 rpm.

The stock mopar O/D is a .7 overdrive as opposed to a 1 to 1. If you went with 4.10s or 4.30s as Rusty suggests it may be a lot of fun around town, but may not be on the engine if you decide to take a trip with it on the freeway for any length of time. Otherwise go with the 4.30s if you decide to take a long trip and want your engine running close to 3k for several hours just to keep up with traffic.

These numbers are very close approximations to what your gonna get with a 27" tall tire which is approx what you have 255-60R15 and you O/D in 4th gear

3.73 + 73.7 mph = 2500 rpm
3.90 + 73.2 mph = 2600 rpm
4.10 + 75.0 mph = 2800 rpm
4.30 + 74.2 mph = 2900 rpm