From the description on NZ Birds Online it sounds pretty good if it was a smaller individual:
The oriental cuckoo is a slender, medium-large cuckoo, about the size of a blackbird. Its proportions and shape are reminiscent of a small falcon. The plumage is variable, either dark grey, or rufous with heavy barring on the back, but all forms have white underparts that are heavily barred with black. All records have been between October and April, which is when oriental cuckoos migrate to Australia between breeding seasons.
Less likely to be a Shining cuckoo if it was near-blackbird size, grey on top, and perched on a fence. Oriental cuckoos are at least twice the size of a Shining and they saw it from 10m away. The call is pretty distinct too but their description does not narrow it down.
! This just came across my inbox from the ebird alerts. Does anyone have any more information?