I am getting ready to pull cab ac compressor off. I would like to know what belts I need to get to make it work with out ac comp . I have 1987 28ft Barth 454 chevy. motor no smog pump . thanks

Simply measure the span with a tape measure.
Loop it around the pulleys you want to cover.This will get you in the ballpark as far as inch length.
If they are double row you will need a matched set.

Paul , I just replaced my engine with a 454 ho, no smog pumps , no ac compressor.
I used 2 7410 (3/8 x 41) belts for the power steering pump . The one belt is pretty close to the pulley but has been working well . I didn't feel safe with only 1 belt for the steering & brakes .
Hope this helps , Bob