Gary,
   I used seats and rails from an old Honda CRX.  They had to be cut and
narrowed by 2" and are heavier than the stock seats, but I got slightly more
fore/aft travel, I find them much sturdier and they have fully reclining
seatbacks.  We  trimmed a lot of metal from the sides of the seatbacks that
wasn't needed, which helped keep the additional weight gain to a minimum.
   I don't know where you'll find rails that are any lighter than what comes
with the kit.  They need to be beefy if you want the seats to stay attached
to them in any kind of impact.
   Skip Slater