The X is kinda stuck between modern and vintage as well, and seats are hard to choose. These are on the vintage side but are my current favorites:
http://www.ebay.com/itm/new-Zagato-...Parts_Accessories&hash=item2c55be8134&vxp=mtr
I think they would look especially good in a very stock looking 74 with the red and brown interior:geek:
Have you seen a picture of an x with the lotus seats? they add alot of elegance to the interior.
Some seats to consider....
I installed Honda S2000 seats in my X with no mods other then drilling four new holes through the floor and bolting them in. I installed factory honda seats belts and I love them. They aren't cheap in Red like mine they'll run you over $2000 for the pair and that is perfect condition used seats but I have seen them for as low as 1200 in black. You do sit a little bit higher which I don't mind being only 5'7" but the support is truely awesome and they look exotic.
'PeteX1/9
I also have the S2000 seats, as does Clark. They are a great fit. I found I had to make brackets to secure them though. They sit low to the floor. I can always measure the offset, however if they are local to you, I’d just go sit in them & see how they feel.
Side bolsters require more than just foam piled up, you need frame structure to support the foam bolsters or they just flop over and don't hold you in place. If you are over 21 years of age you may not be able to get in and out of a race bolstered seat if the top is on.