Resurface head and replace valve seals etc at time of headgasket replacement or not?

Did you find any signs of a leak in the head gasket? There should've been a rupture between coolant pathway to cylinder head on either side of the gasket. If you can't find that. You can find the EGHE hoses. Plug one end and do a pressure or vacuum test on the other end to see if it holds pressure or vacuum. Keep the pressure low so you don't stress the seams of the heat exchanger. That would give you a definitive answer. Do the same for the EGR coolant tubes too.

Good Luck...