Most of your other notes here pre-date the J2 POD, but I wasn't really settled on an an alternative Pope until writing the chapter. Originally, I had considered Giovanni Colombo, assuming that with two popes dead in such quick succession, he would feel compelled to emerge as the compromise. Then, I planned for Sebastiano Baggio, but I didn't feel there was enough about his theology to go back to him if I wanted to. I settled on Hume because I felt he could represent a good compromise ideologically, even if regionally he was a dark horse.
I remember reading about how Colombo allegedly stated that he would deny his own election if it looked as if he would win.
As for Baggio... there's a rumor that he was a Freemason (unproven!).
To be honest, a hypothetical 1981 Conclave is so unpredictable! The ones that would be very qualified in being elected mostly died during the 80s or 90s.