Wellington is 21 hours ahead of Portland
Best overlap: 11:00 AM to 6:00 PM in Portland is 8:00 AM to 3:00 PM in Wellington.
Target 11:00 AM to 6:00 PM in Portland, which lands at 8:00 AM to 3:00 PM for the Wellington side. The overlap is wide at 7 hours, so you can protect mornings for deep work and still find plenty of meeting time. Because of the gap, Wellington is already on the next day, so confirm you're both talking about the same calendar date.