Gear manufacturing

[TomG]

You can either mount the blower 180º rotated (maybe not practical), or make a simple gear train (two gears) to reverse the rotation and use that to drive the belt. Not sure what rpm they'll be running at, but if it's high, they'll need to be helical to keep the noise down. Suitable gears, bearings and seals should be available from places like McMaster Carr, or Boston Gear. You'll also need to design a suitable enclosure so they can be run in an oil bath.

Tom