Not sure if this helps but

horsepower torque wise it would work out to

T=P/(S/5252)=(1/6 HP)/(172RPM/5252) = roughly 5 ft*lb(f) torque

There would be some power loss of course from the use of the pulleys, belt, etc.

So how much force would you estimate it takes to turn the mill by hand, and how far is your hand from the center of the crank? i.e. if it estimating the hand is 6 inches from the center of the crank and it takes 10 lbs force to turn it by hand at a speed of about 3 revolutions per second then the motor would probably be a close match?