Go to www.oldomc.de. He has sales brochures from '40 thru '70's and I'd doubt that they would change the gearbox on a later model 3 cyl looper of that hp, so look in one of his '70's brochures. The sales brochures have gears posted (like 13-26) which would be 2:1. Your 70 is probably running in excess of a 2:1 with that gearbox.
