I did the seats on my Shelby years ago and am in the middle of doing the seats on my Cougar. I was thinking of doing a project post here, but unfortunately haven't had the time yet. Hang in there, it's do-able, and I'm no expert. The seats I'm doing for my Cougar were in really bad shape. I did use new burlap on mine, I sourced the burlap from a local JoAnn fabric store, it's cheap. I saw an old post on another forum where I think our own member Royce P. used a different, more modern material on some seats of his. There is also a jute/horsehair stuff that is used to reinforce edges, I pitched that and used a polyester batting I also got at the fabric store. I also had to go to the hobby store for piano wire to replace some of the listing wires used in the seat covers and the reinforcing wire in the burlap. On my Shelby no one made new foam kits years ago, but my foam wasn't too bad, I was able to reuse it, but had to build up some worn/compressed areas with some new foam I attached with spray adhesive. On my Cougar seats I'm doing now, no one makes exact Cougar foam, it's modified Mustang foam kits. One issue I've found is the shape of my new upholstery covers are not exactly the same shape as the Mustang foam, so I have also had to build up some areas by adding a little foam with spray adhesive. Just be aware that may be something you will need to do also, seems like none of this stuff ever goes easy. And you are right, there is a reinforcing material molded into the foam, that gives the hog rings something to grab. I'm lucky also to have a good foam/upholstery shop near me ( Minnesota Foam & Upholstery ) where I have bought my small foam pieces, just an FYI I think he said there is a specific automotive spec foam ( maybe fire retardant? ) although it looks the same to me. Years ago I had the seats on my '68 Torino GT repaired by a local auto upholstery shop, boy was that a lot easier lol.
