Nor did the DC10 have any sextant port. The story I heard regarding the port on the 747 was that Pan Am did not have complete confidence in the Carousel INS as the certification process evolved so this was their worst case back up solution.
Doubt if Pa Am allowed any "free lance" navs on the flight deck but Chinese navigators may have been onboard to monitor during the initial flights. Probably looking for any intelligence points of interest in lieu of any meaningful nav assistance.