I've dealt with these guys in the past when I needed covers for my white interior and everything was really nice. You may want to talk to them if you have any questions.
Just be aware that the "comfortweave" inserts sold in the reproduction Deluxe covers is merely an embossed pattern, not a true woven vinyl like the originals. You would need to contact SMS to get the correct Comfortweave material. The original material breathes, the reproduction does not. I don't know if Mustang Market makes their own seat covers, or offers another manufacturers products. Fairly sure that TMI will use material that you buy from SMS to make the covers if requested.