Wellington is 2 hours ahead of Melbourne
Best overlap: 8:00 AM to 4:00 PM in Melbourne is 10:00 AM to 6:00 PM in Wellington.
The best time to meet is 8:00 AM to 4:00 PM in Melbourne, which is 10:00 AM to 6:00 PM in Wellington. 8 hours of shared hours is more than enough — slot meetings wherever they're most convenient for the people involved.