I pondered the thought about building my own meat grinder with pullies. However in order to get the RPMs for 60RPM (who turns a hand meat grinder that fast for hours?) I would need a 32 inch pully and a 2 inch pulley!
I am still looking at the posability in building one, but am going use a gearbox ie either a worm screw or actual gears vs the pully set up. The hardest part is finding the gear reduction at an affordable price.
I have looked at smaller and cheaper meat grinders ie 1/3 hp meat grinders, Kitchen Aid attachments and they are really NOT designed to handle large amounts of grinding ie 40-50lbs ie butchering deer, hogs, a whole cow. In fact I have worn out two small meat grinders doing this. Not that my personal experience is the end all, but I feel the way to go is to buy a real meat grinder like the ones you want.
Also you can make your old meat grinder perform like new by sharpening the the front edge of each cutter, NOT the flat face. Sharpening the flat face will ruin the cutter, but sharpening the front edge does not and is the right way to sharpen the cutter.