What else is on this feeder?

As far as the branch circuit is concerned, you can round up to 175 amps by applying the exception to 430.52(C)(1), it is possible to go larger if the motor will not start without tripping this breaker, see exception #2.

I've led a sheltered life, can you tell me what an MCP is?

Few things are harder to put up with than the annoyance of a good example.