I have an opportunity to buy a 1977 KX 400. It hasn’t been ridden for the last 5 years and is stock. The owner claims the motorcycle worked good prior to it being stored. The owner of the bike recommends cleaning the carb/jets, clean and re-oiling the air filter, replacing the gas, which is easy to do. The front brake does not work but the owner thinks it just needs a new cable, and tires. The motorcycle has not been ridden much. What is it worth, what type of riding is it good for, and any thing I should check before buying it. Thanks