Ive only been a member of this club now for *looks at clock* about 5 mins, so excuse the noob-ness.... but on the next page someone as fitted s13 coils and hubs to the front.. and i myself have fitted s13 hubs and coils to the front of 2 of my r31s, so you should be able to run an r31 strut in a z, as long as your prepared to run r31 brakes.
Cheers, Alan.