The old Intl 345 is a real workhorse. They are good for a lot of miles. There is also a big brother engine as the 390 cu in. The speed for your bus may be a little slow with a high number rear axle ratio. If ya wanna determine the ratio, jack up a rear wheel. Make a mark on the driveline and the raised wheel. Make the mark on the wheel at the top or bottom for ease in noticing mark's start position. While looking at the driveline, have a helper turn the wheel one complete turn. Count the driveline truns very carefully. Usually the rear axle ratios are typically 4:10, 4:60, 5:60, 6:80, ect.ect.
Ask lots of questions. Carefully pick out the good answers. Every one wants to help... Frank c
CROWN BUSES ARE GREAT.