John
You might want to check with the General company. I was helping a
friend with a new to him lathe, one of the General 160's with variable
speed. It uses a single fixed pulley on the shaft of the motor and a
fixed pulley on the lathe spindle. These are connected via belts to a
movable pair of pulleys on a jack shaft. For General this is old and
established technology.
On the other hand, if you have it working, why fix it?

Darrell Feltmate
http://aroundthewoods.com