Damaged brass seat is caliper???

I have never done this on a KH caliper but I have on a Master cylinder. take a screw that will tighten into the seat and pry it out or an easy out might do it too. I have removed seats and been able to reuse them.
Dana67Dart, although this forum thread was a few years ago, here is one source for brass tube seats.

Brass Tube Seat | Muscle Car Research LLC