I was in your boat for a little while, but then I realized that who am I kidding, I can never afford 3k for wheels haha.
HaaJeHaa is dead on about the stuff you'll need to run at minimum. Coils and camber plates are a must. I believe the 16x9 Wats have a -13 offset. You'd have to stretch a tire for sure, I doubt a 225 would be enough, maybe more of a 205..? The tire stretch debate is probably one for another day, but just ask yourself if you feel like exposing the bead of a 700 dollar wheel, 4 times over...
Have you ever been to the Watanabe site and checked out all their photos?
http://www.rs-watana..._new/nissan.htm
S30s are down the page a bit, anyone running 9's I believe has flared their car. There is a guy on this site named Lalit0 (I think) that has 8.5s all around, and it is a TIGHT fit. Here's a photo:
I wish you luck in this pursuit, please post images/details as they develop.