In reading your post today while you said the headliner you purchased says late 49' it is obviously not as it has screw holes. The correct headliner for the floating bow does not have screw holes on that edge. I still think the only option with your door weatherstrip is the floating bow. You will need to source the correct headliner for that application. As for why the other is in place I think you answered your own question. It is the vagaries of production and sitting here some 60+ years later some things we will never know.
