Steering column turn signal lever bolt - 72 Dart

I am rebuilding my steering column in my 72 Dart. My turn signal lever was missing, I found the screw in the turn signal cam but it has been broken off. I need a replacement but do not know what size it is. It looks like a special bolt and I have googled for one but am not having any luck.

Does anyone have an extra or does anyone know what size it is or where I can find one?