I have an S-Trim with 6" crank & 2.75 head unit pulleys on an Lt1. Anybody know what belt to use?

 

For future reference I will answer my own question that it requires an 8-rib 40.75 belt, but if you could find one a 40.5 belt would be optimal, but the next size down that I was able to find from 40.75 was 39.875.