Assuming they are in good condition.....
Bluebird builds a good bus. I may be biased though..... TC2000 is a respected model.
5.9 Cummins is a good motor. In that year it will be mechanical. A good thing in my opinion. Much simpler than the electronic versions.
However...... a 5.9 in a full size bus could be a bit under powered. The transmission & rear end gears will be a big factor.
A TC2000 with 5.9, Allison AT-545 transmission and 5.38 rear gears is great for picking up the kiddies in town but will be a DOG on the highway and in the mountains.
The same with an Allison Mt-643 (or 647) and 4.44 rear gears would be better on the highway but not my ideal.
If they have the Allison MD-3060 then you have a reasonable highway coach.
Personally, I prefer a bit more displacement and horsepower in a rig that size. My ideal would be the 8.3 Cummins and the MD-3060.... Again, I may be a bit biased