Thanks for the infos. I really must try to catch the owner sooner or later. It is a two-door-version. When the oldest, as you say, are from 1981, it's indeed a question, if this specific one is an original, as it has a "H"-plate, a historic registration, which you -regularly- can get after 30 years.
The vehicle has to be original for that, but conversions in the old style, with parts and features, which were existing in that time, are accepted, too.
So for example a 1977 Bugatti-Replica on a VW-chassis is o.k.