Dont know if it is a South Bend lathe but maybe this can help you:
http://www.wewilliams.net/docs/Belt%...20No%20600.pdf
If you can't find leather for the belt I would at least try with a rubber belt.
The site where I found that pdf has more interesting things, take a look:
http://www.wewilliams.net/SBLibrary.htm
Good luck!