I have been looking at this for a while and its easy enough to do
I need a high accuracy lathe ,A CNC one I have designed the headstock casting and bedways (to take linear guide rails) and also a large bore spindle to take a D1-4

There are a couple of issues that brought this about namely that small chinese cnc machines which are converted are a bit of a compromise and the boxfords with any kind of capacity are like hens teeth

So I designed my own on the basis that most of the stuff is bought

Linear guide rails
Ballscrews
Pulleys
Belts
Chuck
VFD
Motor
SERVO/Steppers (steppers will be fine)

Spindle is machined and ground

on that basis I can get 3 stress relieved castings made but I have to get them cast in 10s to make them cost effective The costs arent that great but it would be a waste to pay for the castings and then do a one off

Is this something that's interesting or would it be a better bet to but the amadeal lathe bed and headstock and modify from there to suit ,I still think the spindle would be too small using this headstock casting.

Maybe theres a market for a high quality machine or do the mini lathe CNC' conversions provide enough for people into this sort of hobby,light production thing