If I was you, I would try to get in touch with the former owners and ask to speak to a driver. They can probably get you rolling in about 5 minutes. I remember once, my brake lights quit working. I noticed the wiring was in pretty bad shape around the lights, so I rewired it. Nothing. Changed all the bulbs, nothing. Couldn't get fire anywhere on them. Finally, one day an old mechanic came over. First thing he did was check the wiring on the front panel. It had a fuse. It was blown. I spent three days trying to figure out what the heck, he came in and fixed it in two or three minutes.
So, get someone on the phone who drives those buses. It's probably something simple. I would do that before I went to snatchin' out drive shafts, etc...