Not sure what you mean by "120 to 35mm", but the Yashica 635 twi lens reflex camera has a film gate mask and two different spool inserts that allowed you to shoot either 120 rollfilm or 35mm film in the same camera. The viewfinder groundglass also had a red rectangle showing the 35mm film capture area. One could look at that camera as a way to see a 120 and 35mm dual-format camera.
You do need to clarify. There are at least three interpretations of your question that I can think of:
You want to slice 120 down to a 35mm width and perf it. Prohibitively expensive.
You want to copy a 120 negative to a 35mm negative. There are two ways to do this. A: Make a print and copy it on a copy stand. B: Put the 120 neg on a light box, put the light box on a copy stand and photograph it with reversal film.