I have the MM3 and avoided that motor with the advisement of Fred Francis (of MM). He directed me to get something with over 50 in-Lb of torque. Also, his advise was that as close to 175 RPM, the better. I was going to go for 233 RPM, but he said I'd like 175 better.
With my install, I wanted to mount the motor directly behind the mill and in the same vertical orientation for space reasons. Mine is installed in a pull-out shelf inside my brew table, at the right height so that it rests on the paint bucket when extended. It's a 100lb capacity shelf mechanism and I'm probably at around 80 lb with a full hopper. You can see it in operation on the video below (I'm still gussying my rig up a little).
So, the thing not to fret about is the actual motor. You can find ebay deals on 1725 RPM motors easy. Mine was $40 for a GE 1/3 HP motor (I wouldn't go below 1/4 HP). What you need then to avoid using pulleys is a gear reducer. I have a 10:1 gear reducer and this gives me 100 lb torque w/ the 1/3 hp motor. My gearbox was $100 new from the factory. It's aluminum, so very light. The motor is a beast and very heavy. To marry them together, you'll need a Lovejoy connector that fits whatever shaft sizes you have. You can see in the video that there was '''just''' enough room to install these all together. There's probably like 1/4" in between the hopper and the motor housing.
Here's the link. I have the RA40 model at 10:1 ratio reduction. (I was going to get the 7.5:1 ratio to give me 233 RPM and Fred advised not doing that).
They have some going on ebay too, and that's a guy at the factory. If you want to install anything like I did (with a right angle), I highly recommend this unit as opposed to searching forever for a right angle gearmotor. You'll never find one with the right power and speed ratings. And, when you do it will be expensive. Even used. Actually, even used gearbox reducers are expensive, and all the ones I found require a separate bracket to mount vertically like I did.
This is the only one I found after a few months searching that comes stock with mounting holes in every direction including vertical. A good deal at $100.