Daty,
You can bump the belt length a couple inches one way or the other by changing pulley sizes or running the belt outside or inside the tensioner (if possible). I was able to find a belt for my Mag serpentine swap by changing my tensioner to run on the inside of the belt rather than the outside. This took a pulley swap from a Jeep I-6 I grabbed from the salvage yard.

Here's the Gate's on-line belt catalog for micro-V belts. You'll have to go to the end of the catalog to find 7-rib belts. PN's will start with K07xxxx (K=micro-V, 07= # of ribs, xxxx= length in mm).

Clair