I flew at least 3 North Pacific trips in late 1971/72 on -436's. We went eastbound all the way to Tokyo-Honolulu-San Francisco then turned around and went back the way we came!! It was a killer with the time changes and then reversing direction.
The first one I did by deadheading to replace somebody in Honolulu and went West bound with Qantas. I then picked up the -436 for the trip home all West bound. Round the world in 8 days and felt fine. The next one was the regular schedule and it was awful even for a young lad.
Speedbird 48.