Originally Posted by bikemig

The drop out can be modded to work with a campy/suntour RD. The easiest solution is a derailleur on a hanger but you'll get a lot of flack for that. The easiest mod is to simpy tap out the derailleur hanger; a shimano crane or a campy rally will work (at least the first gen as it has a stop). This is a nice easy mod and you can still run a simplex on this.

Otherwise thread the drop out and file out a hanger.

Simplex derailleurs are getting harder to find as time goes on.