Sure, there's threads on this. But cutting out the foam isn't really an option. I'm suffering from the fairy dust effect. I just got back from a car/boat cover specialist. Old Skool shop. The guy wouldn't even try to replace the foam. He told me if he stitched it, I would see the double stitch holes and gluing another layer wouldn't hold. I asked about a layer of felt & he told me the problem is that the cover is uniquely shaped after all these years. He said buy another. He mentioned Acme in California. Anybody know this place? Anybody have another source?
Two possible sources are: GAHH And Cabrioworld.com There is a thread on here somewhere giving high marks to GAHH, the Cabrioworld has an ongoing ad in one of the monthly F car news letters I get in my email. I have been considering a black canvas one from them. I believe Cabrioworld has leather and canvas replacement tops, seems most of these you will have to reinstall the Tanex fasteners yourself. So ask if they come with the top.
Check out JK Auto upholstery on eBay. I just got new seat leather from them and couldn't be happier. They were great to work with shipped fast and the color was a perfect match.