So, is the motor that's already on it bad, too slow, too fast, too weak, or what? Because if the motor's just bad, why not just order another like it?
Another option - it doesn't look too hard to add a lower mount for the motor and use a heavy chain/sprocket speed reducer on pillow blocks if the motor's too fast and too weak to do the job as is.
It would be a lot easier/quicker to help if we weren't getting the info in dribbles instead of posting all known info in one shot... Steve