Hi Robert,
Ancestry online Electoral Rolls have large gaps between the years available but if you can find the full rolls at a major library, public record office or FHS a search of years 1959/1960 for that area looking for a Robert CHRISTIE motor mechanic might help.
Geesh how many garages were there in that area in 1959/1960?
If he was 54yo (or there abouts) there is a good chance he was already married so may have fibbed a bit.
NZ BDM is online (just google) I could not see a definite for him but maybe you can pick a few possibles and try to trace them back to VIC.
Most NZ cemeteries are online also so might be worth a search there.
Also try NZ Archives.
Kellie