I think all the 84 GT owners should get together and send a list with our names to the resto companies asking them to manufacture correct upholstry kits for our cars.
I had the same problem finding covers for mine Have the red interior in mine ... however I was lucky enough to go to a glass/ upholstry shop and they have Ford catalogues with actual Ford fabric ( not after market) they were able to order in new fabric and they are going to recover the seats to look original its a bit more expensive 350 Cdn per seat but well worth it to have it original.
There's an upholstry shop back home I was thinking of having them made if I can find the material.
What is the name of the shop where you had yours done? I need gray, maybe I could buy the fabric from them.