That looks like it was designed after the SouthBend or Myford lathes. Have you picked up a copy of, or they may be a PDF around, of "How To Run Lathe" (very good book that will help alot)? I believe it would help you guys a lot. Its pretty basic stuff of the controls of a manual lathe and the differnt types. For something this old and design it should guide you quit well. I see them on Ebay and many other places. The brake down of the parts of the SouthBend or Myford would also probably help you. Thats what they call a double tumbler gear drive with the trans for changing the gears it has in that pic. SOme of the 9" and 10" SouthBends have that exact same setup.
Here is a link to a site that does have and show a lot of lathes.