It can denigrate into Ford vs. Chevy discussions but there are some good reasons to avoid Ford buses.
First, Ford stopped making any medium duty trucks or bus chassis a long time ago. Getting FOMOCO parts for older Ford trucks can be a problem.
Second, depending on the engine it might be easy, difficult, or nearly impossible to find parts. If it has the Cummins 5.9/B-series engine, easy. If it has the Brazilian Ford diesel engine, difficult. If it has the Ford truck gas V-8, nearly impossible.
Third, depending on the braking system it might be easy, difficult, or nearly impossible to find parts. 'S'-cam air brakes, easy. Wedge type air brakes, difficult. Hydraulic, particularly Girling, nearly impossible.
IHC on the other hand supports their equipment really well. You can still get brake parts from IHC for K- and L-series trucks made in the late '40's and '50's. Some of the odd ball diesel engines are a little hard to find parts and some of the gas engine parts are little hard to find. But most of it is still available. A new Holley carb for an RD501 probably not but the kit to rebuild it is still available.
Personally, I do not like Ford chassis buses.
The older ones with gas engines were gutless and thirsty comparted to GM and IHC buses.
I have never liked the way Ford chassis buses drive either. They have always felt clunky and drove like a "truck" compared to GM and IHC chassis. IHC started on egronomics for school bus chassis a long time ago. Controls, gauges, and sightlines were always better in IHC chassis buses.
So I guess that I would say is unless the Ford was a give away prices I would stay away from a Ford and purchase an IHC.