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.
Here's the front cut line. I'll have to fabricate a new solution for holding the seat belt, should be easy enough:
Ninja edit: I may jump one more spar rearward to avoid having to mess with the seatbelt system as much.
Here's the rear cut line. I'd rather just not mess with the structure around the engine bay, windows, and engineered header in the rear. Externally, the high roof will ramp down into the forward edge of the engineered end cap structure.
I'm all ears on opinions with this, or if you have a better suggestion for a rear cut line. I'm relatively determined to keep the front end short, so it doesn't look like a beluga whale.
One more glory shot, no more interior roof panels!