From what I can remember, you can't stick 5-lug hubs on S13 spindles. You'll need S14 spindles (and ball joints), too. Of course you'll need 5 lug wheels and brake rotors with 5 holes to complete the conversion.

I've read that you can put Z32 hubs on S14 spindles, but I'd confirm that with the local nissan gurus before I tried.

Chris