The biggest thing is that if you decide to do a 685 kit (or alone those lines) I think you need a different cylinder. Beyond that, check the doohickey and broken/missing bolts, and ride the wheels off it. As far as parts, very little has changed on these bikes in 25 years. Finding parts really isn't an issue.
Alcan 5000 Prep HERE
"If you're in control, you're not going fast enough." -- Parnelli Jones