Good question - these cars are actually remanufactured by Nismo and given new chassis numbers (R34-Z-nnn). Still, I think there would be significant issues in complying one for road use directly from Japan...
Having said that, the evidence for the Skyline R34 already exists and most of that would be the same for the Z-Tune, I dont know if a RAWS could work it that way though. Powerplay would probably have done the homework...