The steering stem bearings wear out, as do the wheelbearings (after 70.000 miles or more), . Have a look at the swingarm pivot too, and see if it's clean and greased. Most have never been, and are hard to replace.
Make sure the headers and pipe are in good shape, as these are expensive to replace. The same goes for most of the chrome parts.
The rearshocks can sometimes be worn out too, check if it still has some damping at least.
The engines on these bikes are pretty strong, they almost never leak or use oil. The elctrics are not bad either considering it's a 30 year old bike.
Testride it to see how it runs. It should pull strong throughout the entire rev range.