Don't have an answer for you but my thinking is the same as yours. I have a 39 3/4 (missing the cool artillery wheels) and i'm trying to figure out how to put early 50's bendix brakes on the front. I'm hoping there are some disk brake converters out there who will part with their old bendix units. There were some freebies advertised but I could never get with the fellow. If I locate a set, I can then start the process of seeing what matches up. I would probably start with the backing plates and work my way out. Might, however, need to change spindles. If you know something I don't know, keep in touch and share. Maybe we can work this out togeter.