Business class on all UA longhaul international flights is marketed as Polaris, regardless of whether it is in the Polaris seat.

To answer the OP's question, I am 5'11" and I don't mind climbing over my seatmate when sitting in the window of the old 2-2-2 Diamond configuration. Odds are that you will actually have the new 1-2-1 "true Polaris" configuration though.