Are those BMW E21 Recaros? Nice seats for sure, but better suited for an 80s car IMO.
Anyway, if I were replacing the seats in my Z, I'd go with seats from a 944 or 911 (which are heavy, but look the part), or a set of these:
http://www.classiccarseats.com/st-seats.php
Period correct looks and lightweight. Very expensive though, and they don't recline, if that bothers you.