I remember when the Wellington Aero Club operated two Cessna 180's ZK-BUS and ZK-BKG.
The pic below shows them together at Wellington. (Lyall Bay under the cowl of BKG).
ZK-BKG , c/n 30376 , spent a couple of years on the US register between 1953 and its registration to the Wellington Aero Club on 5-10-1955. It received its NZ C of A on 17-10-1955 and was first flown the following day by Cliff Andrews (designer & builder of the Andrews A1 ZK-BLU). It was sold to Aerial Work (Marlborough) on 11-02-1960; went to the North Otago Aero Club in October of 1961 followed by a hire to Southern Scenic from late 1962. Brian & Frank Hore of Gimmerburn and Nokomai Stations operated her from early 1963 until passing it to Rex Aviation in April of 1972 for onward sale to the Richards family of Hororata and Darfield. Richard Royds of Aoraki Mount Cook Ski Planes joined the list on 17-04-2003. It is still very much alive and well. Pic below taken at Ashburton on 16-01-2010.
ZK-BUS , c/n 30949 , came along a little later. Joining the Club on 19-08-1957 & gaining its C of A on 13-09-1957. It had an interesting event at Paraparaumu on 24-12-1958 when it was blown onto the Auster ZK-ATP. Both survived to fly again. It was sold to and listed with Syd Lister of Temuka on 23-01-1963 and remained with him for something like 37 years, until passing to Terry Hewitt of Wenderry Holdings of Ashburton on 18-07-2000. Pic shows ZK-BUS in its hangar at Ashburton on 07-02-2009 which it shares with the Cessna Titan ZK-NDY.
That probably means that the photo of them both together at Wellington was taken between August 1957 and February of 1960.