Thanks for the welcome Robin!
A few years ago I passed on a local transit bus (i.e. not a school bus, but looked like a school bus) with a Cummins 8.3 and Ally MT643 in it with a little over 130K. When I was looking at it the owner lowered and raised the chassis (air ride suspension?) which was really nice. They were asking 5K and I almost bought it, but it was a little too much at the time.
After reading this site for a awhile I started looking for the engine/tranny combo in my bus. Had to go 1K miles to get it, but get it I did!
I have already started on the conversion by removing all the seats. I plan on ripping up the floor tonight, but don't expect any rust since it was an AZ bus and there is no rust anywhere else, but we'll see.