Replacing foam gaskets

As I was disassembling my 1967 Dodge Dart 270 (225cid L6), I noticed that most of the foam gaskets on the body had not performed their job very well. Perhaps they did, since I don't know their primary function, but most of them bonded to the body by means of surface rust. This is especially true of the areas that retain a lot of water (e.g., the tail light gaskets). They all need to be replaced.

Does anyone know of a better gasket material out there? Or should I just buy a generic foam gasket replacement kit from someone online?

If I'm not making any sense, please ask questions so I can be more clear. Thanks!