Got the ceiling panels removed. That’s a lot of rivets.
I think I’ve got my cut lines figured out. Sorry for the shaky ms paint line. My intention is to ramp it up to keep a neat looking “face” on the front of the bus, and on the rear, ramp down directly into the giant stamped structural member, so I’m not actually cutting or messing with it. It seems pretty seriously engineered.
I’ll have to fabricate a new solution for holding the seat belt, should be easy enough.