I just installed a pair of newly upholstered Fiero seats in a Fiero chassis. They don't appear to be facing straight. Are Fiero seats "turned" a little bit towards center? I know there is more legroom towards the center hump so it would make sense if they were.
I don't know that the rails matter, but the entire seat certainly does lean. Next time seats come up on ebay, look at the pics. Or check out some past sales. The cushions should be interchangeable. The seat frames, not so much. The levers would be on the wrong side, for one thing. I don't know if the seat backs fit at a slight angle, or what.
It occurs to me that this may be a GT thing. The seats I remember in particular were the speaker seats and GT seats from '86. Still, I think the seat lean thing is about the outer curvature of the car--not foot space.
The rails are dedicated right and left side. To switch the seat cushions you have to remove the threaded insert from one side and put it in the other side for the seat back hinge bolt. The seat cushions and backs are interchangeable among years in my experience.
The seats sit square in the car, but the tracks are not square to the seat. Otherwise, you wouldn't be able to slide the seat forward and back on the rails without it tracking in and out. One track sits forward of the other, so if you swap seats and keep the rails, you'll need to mount them out of square on the seat.
[This message has been edited by onesexyfiero (edited 01-10-2015).]