Buy this brackets, where they allow you to use 350z brembo rotors (12.75 inch)
http://m.ebay.com/itm/221388484945?nav=SEARCH
I had them on my car and they are great.
This bracket allow you to use 300zx calipers with 350z 12.75 inch rotors on s13. plug and play. You can get some aggresive 350z brembo track rotors or two piece tmrotors for cheap. I was using factory rotors on my car and it was a great set up.