My car was built in May 1986 and wasn't Cuprinol dipped. It did have wing beading fitted, but was originally painted with the wings on so the beading was painted over.
That is a new one on me. Mike Duncan told me that our 1st Morgan (1985 4/4) had been ordered with wing beading so that it was painted wings off. The beading did not have paint on it. However, by the time we got the car at 18 years old, it had been re-painted so no way of knowing.

Here's a picture from Gregory Houston Bowden's book of a car being prepared for spraying. You can clearly see the beading. I don't suppose you could post a scan of the photo from your later book? I'd be interested to see it.
There is no equivalent picture in the edition that I have. Just looked at my files and the invoice for our 1985 car when new lists:
Separate Wing Beading - £100
Cuprinol treatment. - £30
When we bought the car, Mike Duncan’s advert listed the separate wing beading as a selling point.
If only we knew someone who was working at the factory in the 1980’s.