Kojo Mike

I'm heading back to NZ in December and will be wanting to register and ride a 74 Z1 900 I sent back home earlier this year. What's the go with registering older bikes do I need to do full rego or is there a cheaper option, I'll only be in NZ about a month a year for now. Also who is the best Insurance company to insure an older bike with?
Cheers Kojo