Well, it's like this. I still have some König SK5000 Powergrip seats standing around from a previous project car. I love these seat so much because they are the only adjustable sport seats with that extensive sideway support.
see them here:

http://www.koenig-sitze.de/

So today I decided to try them in my RX7 FD knwoing that it would be a close call to get them in... well they didn't. The König seats have adjustment handwheels on both side which make them to wide to fit.

I, working for a company who fabricates OEM carseats, got to think...
As there are only about 10-15 RX7's driving around in ly country the chance of finding some spare seats to make a project would be hard.

And here comes my question... Do Miata seats fit the FD's seat rails without adjustment? And are they narrow enough?

If ye I want to get me some worn seats for the frames (most important component, safety speaking) and rebuild them