Gfinch,
I am not sure whether to say congratulations or condolences. You think you can get it running, and that is good.
It also needs to stop and cool and suck fuel. Rubber stuff doesn't last nearly as long as the everything else. Plan on replacing the cooling hoses, the flexible brake lines (if one of those breaks, it could be a very bad day) and the fuel lines. Given the age of the vehicle, the coolant has lost all its corrosion inhibitors and the system needs to be flushed. The brake fluid has absorbed enough water to lower the boiling point. The fuel lines were never ready to what passes as motor fuel these days.
So, dump the cooling system and replace all the rubber. You will be dumping all the brake fluid when you replace all the flexible lines. The rubber fuel lines will go porous and cause you no end of grief, but removing them is usually easy as they may just come off in your hand. Use only Barrier grade hose as replacement.
And you just read that and said Oh 5H1T!!, but not to worry. If you do all that yourself A: you will learn a lot about the coach and B: it will probably be the best 1000$ you could pour into this project. (You didn't really think it was going to be cheaper than that did you?)
Oh yeah, the tires are probably toast to. Try to find the date codes.
If an over age tire goes out on the highway, it is guaranteed to do more dollars worth of damage than the cost of a tire. (Providing you survive the experience.)
As to the above, you are not likely to find any diagrams for plumbing or electrics. Just map it yourself and take lots of notes. You will need them.
Does this character know the subject or is he blowing smoke?
Look at the picture in the sigfile. That is our 1973 beauty and she only has 177K on her and I could take her to California tomorrow if I had any reason to go there. As it is, we will be doing the 300+ miles to the Dark Sky Park by Machinaw City next week.
I did once have a 79 D300 carrying a Cayo Motorvator for a while, but I scored Chaumière and she takes good care of us.
Matt