Hello Paul
Ok I will send you a pulley that I think is about the diameter of that motor. If it is larger then you will have to mount the motor with the output shaft hung over the edge of the desk or up on a wood block that is secured to the desk.
Keep in mind that with the extra inertia the motor will want to flip over when you hit the regen hard so secure it to the desk.
When you talk about the motor shafts you say back side and front side. Are you talking about the cooling fan side being 1.125 and the output side having been turned down to 1 inch so that the encoder will fit?
If so then I will send you an H bushing and key for the turned down shaft at 1 inch.
Shoot me a PM with address and I will get this on a UPS headed your way.
Cyruscosmo