If your running a big gear in the rear a od tranny would help put at highway speed, but if you have a 3.73 or 4.10... i would not be running it in od unless you plan on cruising at 90+ mph on the highway when the convertor is locked at 4g.
I would try getting a friendlier cam, going with od if you are planning on Highway driving.
If you just want to play put a 3 speed.