I am planning to jockey a couple scenes around, add some footage, delete some footage, and I think I can easily jigger together a coherent Superman 1+2 set that goes together.
The original idea for Superman 1 was to have it end on a cliffhanger with the Phantom Zone being busted open. For the two movies to work together, I have to remove the subplot of Lois dying and Superman turning back time to save her; he'll turn back time in Superman 2 EOE. I managed to remove these scenes and then not notice anything was missing, so it might actually work.