Should work out good, you will be able to use that large stepper direct drive for the saddle, Z axis. Note that I only needed a 400oz/in for the X axis, so don't overdo that one, but that motor will be the one that limits the voltage you can max out on. Make sure you get a .200" per turn ballscrew for the Z axis and you will be able to get .0001" resolution with a 10X microstepping drive, I used Gecko 201's, very nice drive. I increased my voltage a couple of days ago to 42 volts DC, it was 28 volt and I could only get 38"/ min rapid, with the higher voltage I now get 60"/ min. rapids and am about 20"/ min away from stalling speed. X axis is very fast at 80"/ min. for a small 7" travel with this voltage. Note that the steppers don't even get warm at this. You will need to remove the apron from under the saddle, these usually bolt on. Then need to make a stepper mount and should 2:1 reduce the X axis ballscrew so you can get .0001" per diameter. This lets you place the stepper under the saddle using a belt reduction drive and makes a tidy package. I sealed the entire belt drive enclosure from coolant leakage, which is a must, at you need at least chip protection if you won't be using a flood coolant system. Make sure you add a cover above the Z axis ballscrew to stop the chips from dropping into it. Will be a fun project.