You aren't going to get any visitor's visa based on partnership without evidence of having lived together. INZ are not allowed to take notice of anyone's statement of their emotional attachment or future intentions: partnership, to them, is only proved by the couple having set up home in the same place, with a variety of evidence to show this. Without a long history of sharing a home, and a solid reason for a temporary change, they regard moving away from one another as a break up of the relationship. Your old evidence of former connections would therefore not count.
If he gets an ordinary visitor's visa, for the reason of "look, see and decide" (about whether he can get a job in NZ) and tourism, he would be perfectly entitled to put in a partner-sponsored temporary work visa application from within NZ. Once the application is lodged, INZ would automatically grant an Interim visa to cover him for staying in NZ while the case is being processed, which of course automatically gives you longer to collect evidence.
https://www.google.co.uk/#q=site:enz...tnership+proof