At first glance, it looks like they should work.
You will want to get the higher-current (15A output) option on the servo drive.
Also make sure that the DC motor bus voltage is not too far over 120VDC. Even though the motor is rated up to 180V, the Centroid drive is only rated to 120V.
If your existing power supply voltage is too high, you can just add one of the Centroid transformer and rectifier options. The only consequence of running 120V instead of a higher voltage is that the motors won't go over 3000 RPM. That will still be more than enough speed for a knee mill.
Look for wiring specs on the encoders. There need to be eight wires, some with names like A, A-, B, B-, etc.; also indication of a 5V supply voltage. If there are fewer than eight wires, or the operating voltage is not 5VDC, you will need to replace the encoders. Not especially difficult or expensive, but something to be aware of.