mrpete222 (aka Tubalcain) on youtube has some videos on what to look for when buying a lathe as well as how to run them. I suggest you start there.
I have a 1936 9" South Bend myself. South Bends are very common and Practical Machinist as a fourm section for them with a lot of usefull information on fixing them and maintaining them. The PM fourm also has sections for other makes as well depending on what you find.
Tubalcain Youtube link