Gorton 3u pantograph

I just picked up a gorton 3u in great shape. The only thing missing was the motor and mounting bracket. I managed to snag the bracket from eBay, and I have a few small motors laying around to use. My only problem is that I cannot find the pulley for the motor, or at least some dimensions on the step sizes and width of the pulley. I have the means and the ability to make one, I just need a few dimensions. Can anyone help?