We here at TMI Products actually manufacture the stock replacement seats for your car and we can do it in leather Shoot me a PM if you'd like to see any samples. Also, depending on which frames you have, you're able to upgrade standard low back seats into GT seats by simply adding GT foam & Upholstery... just a thought.
Front seats from a 79-04 are interchangeable, but the back seats on verts pose a more difficult swap. I don't know if anyone has swapped over a newer vert rear seat into a fox. I've been meaning to get the measurements and figure out if the conversion can reasonably be done.
Here is a thread with pics of my 2002 seat install in my 87 FWIW :