Hey Geoff,
I may be able to help with this. Social media (Facebook) has a number of groups dedicated to “Old School” windsurfing. Posst about amazing finds like this abound. Quite a collectors market here and in Europe.
Members include Robert Masters, The Feeter brothers etc….. from the early days as well as pros from the 90’s.
E mail me pics and I’ll see if I can find somebody for this sail.
Wd