I have a No. 4 model C as well. I have some 3d printed 103 spools and roll cut-down aerial film (Kodak Plus-X Aerographic 2402) onto them. I don't have backing paper so I blocked out the red window and just count my turns on the crank between shots. It's kind of an involved process, not for the impatient, but it works.
I process the film in a very large Jobo paper drum. The end result are some really huge negatives. My No. 4 has the original Kodak lens. I don't know that they made it with anything other than a Kodak lens, but I've heard of copies where the meniscus lens has been swapped out for something sharper by the owner.