I got my BBK underdrive pulley set and it says to use a 92.3" belt. Im haveing a hard time finding one, the closest I"ve found was a 92.2", and a 92.6". I was thinking that the 92.2" may be a little small, think I could get away with the 92.6" belt?

Probably. Your best bet would be to run a string around all your pulleys and measure exactly what you need. Make sure you don't forget that the tensioner needs to be in the right spot.