A bit more info on my plans:
If the spindle upgrade goes well, then I'm planning to also add CNC control to the mill.
I have a bunch of CSM servo motors and amps from a former employer that should work well. Two are 3.3 hp (!!!) 4" units that will spin up to 4200 rpm. I'm thinking these will work well for a spindle motor and also a Z-axis knee-drive. I have scads of smaller 2" servos in the 1/2 hp 6000 rpm range that I'm going to implement for the x and y axes. I've got some gearboxes available to up the torque on the small motors. I'm going to leave the quill manual and lock it up during CNC use.
If all my amps work ok (at least one is a little spotty) I'll be controlling everything through Rutex R2040 servo controller and Mach3.
Thanks for looking!