I have had the stuff custom made, and have a roll of it in storage. Contact me at harrisgareth@yahoo.com, and I will add you the the list of people waiting for me to dig it out when I get to the end of my current military duties.
Gareth
Freyja E35 #241 1972
Try WEFCO rubber. They have an extensive inventory of rubber gasketing material. I was able to match up my 1972 E-35 portlight gaskets (both glass and insert) and rub rail material via WEFCO.