I Found A Source For the Upholstery Materials

 My WACO was built to be the Model T of the air.  So it seemed reasonable to look for Model T materials.  Classtique Upholstery has the materials for people restoring Model Ts.

The edge beading is called Hidem Welt.  It looks to be exactly what I'm looking for.  I'll figure out what materials I need for seat cushions, side panels, cockpit coming, etc. and get some ordered.  I have the drawings for the WACO 10 seat cushions.  That should be a good start for making some for the NINE.