Having trouble selecting a belt drive for my router.

To many different options & sizes.
I've downloaded & tried several manufacturer's software selection tools but most are made for constant RPM & HP designs not so much for servo applications.
I'm running 300oz-in cont & 1000oz-in peak @ 2:1 (3500rpm->1750rpm)
Need to keep the pulleys as small as possible due to space restrictions.
Just wondering what other people are using.
What brands? Gates, Goodyear, Browning?
Also is it best to use a smaller pitch to prevent cogging and keep the drive running smooth?
THANKS!
Chris