I have no idea what brand my grandparents old sorgum press was, but if yours is anything like their's was it was connected to the drive animal by a 10' or so pole. Last saw one in operation in the mid 1970's so I have no idea what the ratio of turns was. You'll have to see how many revolutions the rollers make for one revolution of the drive plate. Then figure out how many rpm your engine or electric motor turns, then calculate the size drive and driven pulleys you'll need. As already mentioned, those were slow rpm operations so don't try to run it to fast.
Ken