Keith
You obviously have a different model to mine which is a 1974 4/4 2 seater. At least you wont have the corners at the back to worry about.
I was thinking overnight about my previous post. Maybe I will fix the beading first possibly with double sided tape (carpet tape?). With only a few screws holding the wing the beading may move with body flexing if the wing isn't a tight fit to the arch along its length.
George
I concur about the stainless fasteners but maybe the rusting was caused by moisture ingress not the other way round.
When the beading is on what method is used to waterproof the beading to body panel interface to stop water wicking into the woodwork?