Looks like a great board ,most of these boards have broken down by this age, sun uv ,weather,or being 36 years prime, if the sail is still in good nick, it may be worth while hunting your local yacht club for some old fiberglass battens from some old catamaran sails,cut them down ,get new ends from ship chandler,. The yacht club will point you in the right direction.
The board you have will get you going better than new ones, in minimal winds, and are great fun on a hot low wind day.
Good luck.
Funny
How so?
Any battens that are the old flat style about 15mm x 2mm ish (?) will be fine, find as long as you can and cut them down.
Raid old sails at tip shops if you can't find them at shops and sail repairers.