You have checked the popular (usually B- and E-body oriented) aftermarket restoration vendors, but NOT the manufacturers' websites. As in Steele Rubber Products.
The particular deck lid weatherstrip is something of a generic Chrysler weatherstrip. NOT specific to that particular vehicle, other than its possibly longer length.
"Roll goods" is what the term is for that item. Measure the length, end to end, and then look in the Steele Rubber online catalog to look for the side profile and size of the current weatherstrip. They might also have a listing of what you need in their online catalog!
In measuring the total length of the weatherstrip, add 1-2" to the length you come up with. That extra length will allow the two ends to overlap when they meet, so you can cut through the overlap for a nice butt-end to apply adhesive to and it will look very nice when done.
Enjoy!
CBODY67