I haven't been able to find a race where the Morrari was number 104.
Going by the other cars in the photo - 117 N. Pointon, Chev Coupe, 102 Ivan Cranch, Consul-Jag and 138 Doug Bremner, VW - it could be the December 12, 1964 meeting where the car was not in the programme but did win it's first race. Paul Fahey was in that race in his Lotus-Cortina numbered 104.
At the 1965 NZIGP meeting the Morrari was numbered 122.
This photo is from the Motorman report of the December 1964 meeting.
Attachment 48042
Another possibility is the February 27, 1965 meeting where the Morrari was driven by Glen Jones and was again not in the programme.