V-Belt Sizing

[VFilms]

I'm trying to fit a new PS pump belt on my 318 Poly. Gates shows it as a 9390 which is 39 3/8" but it is a bit too small, maybe 3/4 to 1". The next Gates size up is 2" longer and I can't seem to find a 40" belt. I know there are not a lot of Poly builders here but any suggestion will help.
Thanks

 

[pnora]

Gates 9400 40 5/8

 

[lemondana]

What model car and what year?

 

[Timmayy]

In my experience, most belts are made in 1 inch increments.

 

[VFilms]

What model car and what year?

'66 Belvedere, Poly Stroker.

 

[VFilms]

Thanks, I appreciate all the comments. I found a Dayco 17400 that fits fine. This is an AC car and there is a pulley bracket for the AC belt that changes the PS pump adjustment slightly. I'm guessing this is why the 9390 belt was too small. Thanks again.