Why not just convert the 4 lug to 5 lug? That way you have an infinite choice of wheels, and the added benefit of the larger 87+ turbo front brakes. A nice new set of adapters will run you about $200-250. You could get 5 lug hubs off of a Z parts car for probably that much, then just add a few more bucks to get the rotors and brakes. Plus adapters don't run as well as wheels bolted to the hub. I have adapters and 17s on my 280Z and it doesn't handle anywhere near as well as it did with 16s bolted right to the hub. And I have brand new, wider tires on the 17s than the 16s, I can definately notice a difference.