Verbal descriptions of an old piece of gas & oil equipment are hard to visualize and come to a conclusion as to whether or not you are correct in your assumptions. If you could somehow produce a photo of the apparatus, that would solve a lot of the guesswork. You are probably correct if the pumping mechanism matches the drawing in Jacks book, but a photo would help the rest of us to form an opinion.
Everything Cities Service
Specializing in old Gas Pumps