Bob Drake “used to have” a spongy seal for 35-36 convertible that could be used. His “out of stock” is often I hear.
If you can find the seal that goes in the upper door of a closed car it can be used. However most vendors sell it pre-cut in about 30” sections. I used to could buy it in uncut lengths.
It has an up side down “U” shape and the legs have to be trimmed off. It is then inserted in the header.
I suppose two short pieces could be super glued together to make a longer piece …never tried it