Not the answer to the original question, but on the topic of very large souls on board count in an evacuation, I think an El Al 747 flying Ethiopian Jews flew from Addis Ababa to Ben Gurion with 1087 aboard, captained by Aryeh Oz as part of a mass evacuation May 24-25, 1991.
Many references state there were 1087 evacuees--if true the actual souls on board was still more.
It was a Combi, but fitted with seats. The evacuees were small, and with arm rests raised, the expected capacity of 760 was greatly exceeded.
I don't think they asked Mr. Boeing for his permission.