Personally I prefer the longer plate on my Zed which is mounted to my standard bumper on the plinth still but then on your Zed Bobby the longer plate without the plinth & with your "different" (read that as cooler & better ) bumper doesn't quite look right.
But I don't like the position of the smaller square plate on yours either, ...I think though if I was you I'd go with the smaller square plate but mount it to the left hand side rather than dead centre. Something like below:
Using something like this to do it: http://www.ebay.com/itm/SILVER-JDM-LICENSE-PLATE-RELOCATION-ADAPTER-BRACKET-FOR-NISSAN-240SX-300ZX-350Z-/231153267898