Picking a lathe size for servos I already have

This is sort of the reverse of Jon's thread on picking the right servo for a project - what size lathe would be suitable for some Yaskawa AC servo motors and matching drives that I've got?

I've done one mill control retrofit and I'm doing another right now but I've not studied the ins and outs of lathe conversions.

These parts are coming off of a Tree 425 mill I just purchased and they were put on there by a prior owner as part of an incomplete control conversion. They are both less powerful and slower than the OEM DC servos were so they aren't going to be used. They are pretty obviously brand new. They've been mounted up and might have done a bit of table moving but the machine has never cut anything.

SGMG-05K3A-YA11
450W
2.86 N/m
4.4 A
1500 RPM

It seems like they'd be plenty powerful for the axes of many lathes likely to be found in a home shop. I've got a nice 17" Mori Seiki manual lathe, but it is an inch leadscrew and that means that it stays locked when doing metric threading and most all of my motorcycle projects are metric. I don't want to mess up that lathe, but also having something smaller, say the size of an HLVH/10EE, that was CNC sounds appealing.

I'm in no way looking for yet another tool project right now - I've got to get the Tree up and running and then use it to make some stuff. But I'll either be selling off the three sets of Yaskawa motors and drives or I can hang on to them if they look like they'd be useful for a lathe conversion somewhere down the line. For a two axis lathe I'd end up with a spare motor/drive set and that might not be a bad thing to have around. If I wanted to do a lathe project some day I doubt I could go out and buy new motors/drives for what I have in these three Yaskawa sets (basically, they ended up being free).

cheers,
Michael