Thanks for the info. I'll check around with a few of my past HVAC patients to see if they have anything laying around. Unfortunately my HVAC contractor that did my house committed suicide a couple of years back and they dissolved the company after that. Did the older style furnaces have large pulleys....like 12 inchers? I would hate to blow $38 on one pulley if someone has one in a scrap pile.
I have one in my garage with the entire squirrel cage blower that has a 14" pulley on the fan and a 1.5" pulley on the motor. Came from an old Reliance AutoGas furnace. Lots of these should end up at the junk yard after salvage of copper from motor windings.
Great job on the design and construction of your equipment. I'm afraid to let my wife see your pictures, she'll make fun of my amateur construction. At least mine is all kept in the garage/workshop area.