Barry:
IMHO you would be much better off installing a relay kit close to the starter solenoid. The wire and connections from the starter switch to the solenoid get pretty old and resistance increases over time so that the solenoid doesn't get a lot of juice applied to it, the connection at the starter is therefore poor, and it starts hard. They are sold by Tweeks and Rocky Mountain Motor Works, among others. They come with easy instructions and can be installed in less than an hour.
Oh yeah, it doesn't hurt to have your starter rebuilt, too, but through a long time and a LOT of dunebuggies, I've never seen the need for a high-torque starter.
Gordon