That's a good start but not sure it's enough. I'm not going to lecture you like everybody else, I'm just going to give you a pure driver's perspective.
If you put the risk of other drivers that might pull out aside, I think that 260 is too much on NZ roads.
While I personally think that driving at 200km/h on French highways or 250km/h on German highways is relatively safe as long as there's nobody else on the road (but it's still illegal in France), the quality of highways in NZ is nowhere near to the quality of highways in France or Germany. At 260km/h on NZ roads, you need real skills and there's always the risk of losing control because of a road defect (and you won't be able to do anything about that no matter your skills).
My point is : 260km/h on NZ roads is way too much, if you want to find your limits and learn how to drive fast, you should go to a racetrack. And you'll learn a lot more that way. Anybody can do 260km/h in a straight line, not that much people know how to go fast in corners.