Yeah, I got one too just for the sake of it. The camera that started the revolution. My favorite was the 110B Pathfinder. I had a lot of fun with that camera as long as I could get film for it.
To answer your question, Philip, the 110, 110A, and110B are the models that usually got converted to a 4x5 back, as they had lenses that could cover the film, shutters with all speeds up to 1/500, and a built in rangefinder. Many also also got stripped of their lens/shutter assemblies to be put on 4x5 camera lensboards before the back conversion came out.
Waiting for the light