Jeff
Problem is we are talking about re-using the leadscrews on a small import lathe so they are not likely going to be of high precision.
Katoh
The Chinese can make as good as anyone else, just depends what you are paying that normally determines the quality. I have Chinese ER collets that are as good for runout as any UK or USA made ones and heat treatment seems right as well as they dont seem to be losing their spring and have not cracked yet.
I got ballscrews from a place in the UK, might be worth contacting them. Also worth contacting Dan13 to see what he has to advise as I know he also got some from them but had some issues but think he got them sorted. Mine were 32mm Dia class 5 ground and I am happy with them. This is the place
http://www.motionandbearing.co.uk/Home.htmlHood