If you're going for the Fireflake Royal Blue that Norton used then the House of Kolors is very close. That's what the bike in the link above is painted with, apparently. But, beware what base it is sprayed over. I wanted to reproduce the Royal Blue that my bike was originally, and the House of Kolors chip looked an exact match to the original colour in the sunlight. However, my painter used a dark base, so my tank and side covers came out considerably darker than I expected.
Luckily, I like the result, but it's not an authentic colour anymore - call it 'custom'.
Like you, I tried to get paint codes etc at the time I had my stuff done but got nowhere. Matching chips was all I could come up with at that time. I'm not sure if House of Kolors is available in NZ though.