For a 53 3/4 ton cruiser, I will reccomend...
1. A full pressure 235 or 261
2. 4.11 gears in your housing. They can be found in 67-72 3/4 tons with automatic transmissions
3. An A833 4 speed OD transmission. There is a GM version of this dodge transmission that will bolt up to your bellhousing with a little machining, allowing the use of all the stock clutch components.
4. Tall tires in the rear like a 215/85R16 (30.4 inches) or taller.

These changes can all be done as individual projects to minimize down time. You can also see how much each one improves the drivabilty. The most improvement will probably be found when going to an OD transmission. All the changes listed above will work very well with each other, or offer modest improvements by themselves.