Where can I find interior back window trim for a 1965 Jetstar 88 ?

The inside back window trim on my 1965 Oldsmobile Jetstar 88 is molded burgandy colored plastic that matches the car's interior. It is sunbaked to the point of being crumbly. I need to find a similar shaped trim to replace the back window trim completely. With the new plastic paints, I can alter the color match if I can just find a trim molding that works.