The 7.3 is a fine engine, I consider that to be high mileage and would be looking for something with less but if it’s been well serviced and can be documented it may fit your needs. Definitely confirm what transmission is in it, the mountains here can kill them and you fast. Many Ontario spec buses were lower spec with that motor, 2000 trans and hydraulic brakes, in my opinion lower spec Buses because of knowing they can rust out long before they wear out mechanically. Confirm hydraulic or air brakes! Ask lots of questions, get lots of pics and view in person, this bus will be rusty.