You won't be able to fit the Z touring wheels on a third gen--I've tried.
You WILL be able to fit the Maxima wheels--which look the same but are narrower and FWD offset. Those can be found on ebay for ~$550 + shipping for a set, which is not bad at all. Even the Maxima wheels are a close shave. The set I test fitted had 245/45/18 rubber on them, and the tires touched the shock tower (barely) in the rear. With 225 wide tires you should be fine. Of course, this was with stock suspension--I have no idea how things will fit once you've got aftermarket shocks and springs on.
Here's a thread I made a while back with pictures of the Z-lookalike Maxima SE wheels on my third gen:
zerothread?id=123211These wheels are 18x7.5 and I think 40 offset (I'm terrible with wheel stats so I don't recall if that's positive or negative offset).
Sorry I can't offer any advice on shocks--my third gen is stock, so I have no experience with any aftermarket products for it.