Allen:
I have to say that I agree with Gomer. It could be a fun "older" bike, but I don't think it is old enough to be vintage. Who knows ... it might be a fun project. I would try and get your buddy to give it to you and tell him you will give him the $500 when you sell it or if you get it running.
Check with the great folks at Service Honda for information on parts and Eric Gorr's Forward Motion Racing as well. They might be good sources of information on the feasibility of this project.
As you mentioned green sticker, I assume that you are in Kalifornia. That being the case, I can assure you this would be a great bike for Glamis according to members here that have had the pleasure of riding the dunes there.
Also ...
Welcome to the site :cool:
Be sure and go to your User CP and update information relating to your location, type of riding, etc. After that grab a spot on the couch and tell us a bit about yourself. How long you have been riding, what kind of riding you prefer, where you are located, etc. We will do our best to hook you up with some fellow dirt bike enthusiasts.
Again, welcome to the site and shout if you have any questions!