Hello Grogan and welcome from Virginia.
The paint can rattle is the timing chain. There are indeed 1 or 2 ways to fix it. An external cam chain tensioner is the easiest and many have it on their engines now, especially if they have increased the power.
Ask if the bike has the factory upgrade kit installed, this fixes early transmission issues. Keep in mind, most bikes did not have the problem.
Otherwise, look for normal things like tire age, sound when running, does it start right off and so on. Judging from your list of bike, I am guess you know your way around a bike.
And, if you don't mind, go over to the "Introduce Yourself thread" and tell us more about your bike history. Good luck!