not exactly stock, but could you use closed cell foam/EPDM weatherstripping to fill the gap? Like maybe a decklid weatherstrip cut to fit?
We think alike. I was look'n for some good used weatherstripping to try last night. Know i have some in the garage...somewhere... Got to get rid of all the 76-79 TA parts so i can find stuff, and have room to work when i do. Do have NEW GM 76-81 FB/TA door weatherstrips i could cut up...but at $160.00 ea per side(my cost)...