If the HF shaft is too long, just grind the output shaft to the desired length. Don't put too much side/end load on it when grinding, and toss a plastic bag over the motor to keep the debris out. Be easier/more stable than creating shims, and might look nicer. Just a thought.
PM me on the break in procedure for that motor if you want.
PM me on the break in procedure for that motor if you want.