Hi, I'm a Kiwi although now living on the other side of the world in Norway. However I do have a couple of addresses for your mate. Both of these groups are based in Auckland (the largest city) so if your friend is elsewhere, there are other groups.
email@example.com (this is for the Commemorative Airforce South Pacific Wing/Military Re-enactment Society & Jeep Owners Club of NZ)
There are more but these should do or be able to point your mate in the right direction.