Like keith said it is a good bike I have started with a lot less. If your friend does not want to restore it try to get it from him BUT DONT LET HIM TAKE IT APART even if you can get it running it does not need to be fully restored
It hasn't rusted much so it's not likely to deteriorate. It's not a piece of Jap Crap. If the repairs work leave the frame alone. It's part of the bike's history. DO NOT take the bike apart until you are ready to fix it. There are loads of restored 16Hs. There are far fewer with patina. If it were mine I'd do whatever was needed to get it running again but otherwise leave it alone where ever possible
