You might want to consider searching for a twister lathe on ebay or the for sale section. They are very solid, and I wish I had one back in the day.
As for slave motors, you want something that'll run smooth at slow speeds. I think someone makes a 55 or 70 turn motor that can be run with a 6-cell pack or higher voltage. What you want to avoid is a motor with inconsistent torque, since you want the armature to spin at a consistent speed throughout the cut. Good luck in your search.