Portland is 3 hours behind Atlanta
Best overlap: 11:00 AM to 6:00 PM in Atlanta is 8:00 AM to 3:00 PM in Portland.
Keep meetings inside 11:00 AM to 6:00 PM in Atlanta — that maps to 8:00 AM to 3:00 PM in Portland. Portland is 3 hours behind Atlanta, but you still share a generous 7 hours of overlap, so scheduling is easy and there's room to move a meeting when you need to.