You need to define what you are talking about. Are you overhauling the engine? If that is what you are doing Prevost is not going to do that. Only a Detroit Diesel shop or someone equally qualified will do the overhaul. I question why you are doing an overhaul. What specifically requires you to do that.

But no matter what your decision regarding an overhaul, one thing that is critical is the cooling system and if you are experiencing 195 degree temps as normal it is probable your radiator is becoming plugged. Before you ever consider rebuilding an engine it is critical you fix the cooling system so that new engine isn't damaged by high temps. Prevost can replace your radiator or have the existing one recored. I suspect Coach Worx can do that also. I would ask for quotes.