Tough question as I am not familure with the VG30 gearboxes in the 300z's. I would have thought they would be closer to the RB25DET boxes and not the RB20DET box which is a smaller version and very weak.
If it did fit, odds are if the 300z is a turbo car it wouldn't last long. The autoboxes from the R32 range are not strong at all.