That would be Air Hawke's Bay, splat, although it's a hard nut to crack as an outsider because it's all part of the Air Academy Hastings / Hawke's Bay Aero Club family, and it's normally their instructors who get first crack of the whip when it comes to the multi flying.
Just remembered there's also an outfit in Fielding, Air Manawatu I think? Navajo / Chieftain once again.
Also at the risk of stating the obvious, they've got the Metro's in Auckland and Wellington, but I think you've got to buy a type rating off Airwork and stand in the queue for that one.