Hi Dave
I have been down to the workshop and found the bits of the perished rubber seal, it is definitely rubber, curved at the corners.
However I am liking the sealant route, however still need to work out the plywood and roof lining shape as both are rotted away.
Having said that it should not take a great deal of working out( famous last word) !!!
Just a quick one, any recommendations about roof lining fabric ??
Cheers
Ken