CNC minilathe

I'm planning to convert a 7 x 12 minilathe to CNC. I have a basement
full of machine tools so making parts for the conversion is no
problem.

Briefly, I'm scraping the lathe for bearing and alignment, and I'll
make a longer crosslide with T slots to allow mounting multiple
tools. I envision using the lathe to turn small repititious parts,
and also with the tailstock in place to do taper or contour turning
on longer parts.

I have a 3/8", 8 turns per inch ballscrew with 6" travel I would like
to use for the crosslide. I understand this will rule out manual
operation, other than that any downside? I was planning to mount the
16 turns per inch Acme that came with the machine in ball bearings
and make a bronze nut for the X travel.

Need guidance as to appropriate step motor size from someone who has
CNC'd a similiar machine. I'm thinking that the rapid travels
wouldn't need to be as fast on a lathe as a mill, so I'm tending
towards 200-300 oz/inch motors belted 2-1. Any suggestions as to what
has or hasn't worked well are welcomed.