Keep in mind that if you use an external motion controller, you do not necessarily need intelligent drives, i.e ones that close the loop to the drive, I use ones such as AMC etc.
There is a fellow by the name of Jon Elson that has made a commutation converter for Fanuc Redcap AC servo motors, these make excellent large servo replacements and also spindle motors for smaller machines, I think he has also made a drive.
You may be able to use the 5S or 10S size.
Due to the proprietary nature of the commutation, you either need a converter as mentioned above , or change the encoder, which I have done by using the Renco commutation encoders. Other than the commutation, the original encoder is standard differential.
Even using them in the BLDC fashion results in a nice smooth motor as they are 8 pole motors.
You may be able to use the Granite drive on them, as I believe the Granite obtains commutation from the encoder pulses only?
Nosmo.