If a Powerstroke identical to the one in my truck falls from the sky, I will volunteer to try it in my bus.
We ran a 7.3 Powersmoke for a few years in a fertilizer delivery truck that grossed around 28,000. It performed more than adequately. I have owned a succession of 7.3s and now a 6.0 which I realize is generally known as a mobile grenade. It has however got a scary amount of power - I can't compare it directly to any of my 7.3s because I don't pull the same loads but the 6.0 is better although it definitely slurps more fuel. If the 6.7 is really as much better than my 6.0 as I think it is, then I don't see why it wouldn't make an acceptable transplant.