I want to keep Sigil in Pathfinder. Do you think it could work with the Pharasma's Spire and Axis and how?
I'd have it encircle the spire between Axis and the Boneyard. If you wanted to it could probably replace Axis entirely.
Axis is cool as well. So far I think maybe to change it a disc-shaped city, from one side would be the Threefold Spire of Axis, and from the other Pharasma's Palace, and the Boneyard merged with the Dustmen Mortuary. Tough that would require changing Pharasma, calling her the Lady of Souls, or something.
I have a Planescape PC in my Runelords campaign. He took an extra-wrong portal while searching for the ordinal plane, and ended up in a different aeon. It has been great fun to speculate whether it is before or after, especially with the subtle similarities.
This may not help you, but just know that embracing the new cosmology as a part of Planescape's infinite variety is an option!
Yes, the cosmology is easy, it's all a matter of personal views and beliefs, unknowable infinite planes and all. However the city itself I'll probably change into a hybrid, the story is that Sigil reached with the portals into the Great Beyond and Axis liked what it saw and tried to expand its borders. Not just in space, but also in time.
Also I thought about renaming the pantheons (Greek=Iblydos, Chinese=Tian Xia, Norse=Ulfen, and so on), not sure if it's necessary.
