Lathe cross slide conversion to a ball screw

[dagrizz]

I am at a loss to decide if this is a serious comment or not.

Definitely not serious; I just couldn't resist... Actually, I'd consider this upgrade for my Taiwanese 12 x 36, especially if the LH ball screw was available.
[edit]
I just checked at Thompson; they list a 5/8"LH w/ 0.2 lead, 6' long [https://www.thomsonlinear.com/en/product/190-9099]
The nut [https://www.thomsonlinear.com/en/product/8106-448-037] needs a screw-on flange [https://www.thomsonlinear.com/en/product/8105-448-002]. You'd have to machine the shaft to fit, and I haven't researched the fixed & floating bearing options.