Any lathe is only as good as the person operating it, Ive seen guys turn out perfect things on a worn out and sloppy lathe, because they knew exactly what they are doing and knew the lathe like the back of their hand. 

Try to find one with bearings in the head and not bushings. Many of the older South Bends have bushings and they are getting to the end of their really useable life without a major overhaul