The early Zcars, especially the first generation, were very sensitive to wheel and tire balance.
Very few manufacturers still make the zero off-set required by the Zs. If you want something larger than 16 inches there is pretty much nothing available.
Some of the Zcar aftermarket specialists such as Motorsports Auto <
http://www.zcarparts.com> will have a few styles available. Enkie makes a BBS look alike with a Gold mesh in 16 inch size and Panasport has a good selection. Otherwise, search the internet for something for sale. I found a set of Epsilon three piece modulars for $400 last year (No you can't have them!). It also helps to find other cars with the same wheel requirements such as some Moustangs and Toyota Supras.
Start searching the Zcar web sites <
http://www.zcar.com>. Good luck!