Hello , and Welcome to iRV2.
Most RVers will say " Better used and Maintained than stored and ignored "
Are the service records available ? Are the tires OK , Good date code ?
I think that a 41' coach would have the ISC , Cummins. JMHO the ISB ; 5.9; would not be enough engine for the weight of the coach.
The engine/trans combination, should be good for at least double the current miles.
By the year of the coach , I think it will not be a Common Rail fuel system, but have the VF-44 ? pump
The only recurring complaints with this engine involve the lift and injector pumps. A plugged fuel filter or defective lift pump can kill the injector pump. $$$$.
If the coach suits your needs then the miles should not be a factor.