I dont think it would cost that much to get it ride-able. Only issue I can see is that the tires should be changed, they look pretty shiny which usually means the rubber is hard.
For a 75F, 800 is not bad at all. Sure if you want to put it back to stock, it will cost money BUT if you wanted to get a stock F in good shape, you would spend at least 1500 so you come out close to the same anyways.
The bike is close to stock anyways. Most people other than purists, will appreciate the kerker exhaust.
Other than that, paint on the parts and engine and almost everything will be "stock".
Another nice thing is that the F bikes are not nearly as common on the road but will still use many of the same parts.
The ride IS the adventure. The destination is just to get gas!