Melbourne is 19 hours ahead of Portland
Best overlap: 1:00 PM to 6:00 PM in Portland is 8:00 AM to 1:00 PM in Melbourne.
If you set up a recurring sync, 1:00 PM to 6:00 PM in Portland (8:00 AM to 1:00 PM in Melbourne) is the natural home for it. Melbourne is 19 hours ahead of Portland, leaving about 5 hours of daily overlap — enough for most meetings if you don't leave them too late in the day. This window straddles two dates — Portland's today is Melbourne's the next day.