Catt roots and repotting

[Carl]

Hi everyone,
I am not new to orchids, but very new to Catts! I could not resist getting a few to add to my collection. However I did inherit a very overgrown Catt with a lot of roots growing outside of the pot--many of them are older roots that are wiry, white and brittle. It has started to put out new green-tipped roots and it needs to be repotted, but I have concerns about the roots. Should I cut off the older white roots--they need to come off to get the Catt into a new pot. Also, any additional advise on repotting Catts would be greatly appreciated!