If you do buy this and in case it has problems , I hope you are handy at building things and have the room, like a barn, to work on it.
In class C units, the cabover areas tend to develop leak issues. Clearance lights, dried caulking around the seams and roof and unfortunately that large front window are the usual culprits. That's why new class c units do not have them. Find someone like a mobile tech as suggested to inspect it. Money well spent.
Personally, I don't like the idea of a vehicle like an rv sitting unattended and not cared for long period of time. At its age, I would be concerned about water intrusion due to lack of maintenance, dried caulk in the seams.