69 motorhome

[George2]

Someone wants to give me a motorhome that is built on a 69 1-ton pick-up cab and chassis. It has 46k original miles but has sat idle for over 10 years. The intireor of the cab is original and very clean. The exterior needs to be cleaned up but no dents ond original paint. The camper inside is clean and has no leaks, but could use a good remodel.
What are the chances that the engine and trans are salvageable? How about the brakes? Would it make more sense to just put in a "new" rebuilt?
I dont dare attempt to start it. The engine is a 350, the trans is a "turbo hydro-matic". It has duel rear wheels with a 410 rear end.
Is there much value in a truck like this? Is there any value advantage to keeping the original engine? How are the rebuilds that are aviliable? Are they reliable? I assume they are converted for unleaded gas. Is there any re-manufacturer that is is particularly good? I'm trying to get some info before I decide to take it or not.
It is a situation where an eldrly widow has it in back of the house where it sat since her husband became ill and eventually died.It will be donated if I dont take it.
Thanks!
George