Those old 600's were pretty stout. Stator is the big watch as well as TSS. The front skid shock did not have the bracing that the newer ones do and have been known to bend that shaft when the sled is jumped or rode very aggressively. They also weren't the most fuel efficient for what they are. Otherwise not a bad sled for what it was and many parts available. Also, body parts from the newer ones swap over pretty easy so updating the looks is do-able. I personally didn't care for the looks of the 98 and 99 ZR/powder special.
If the price was right though, its a decent trail machine for someone starting out. That's actually what I would like to find for the girlfriend so she doesn't kill herself on my sleds...