I've got an '84 RZ350 that's been babied all its life - my last job as a mechanic was selecting and pulling the crate out of the warehouse and servicing it for delivery. No one has ever ridden it but me and its never been wet. I stopped riding it several years ago due to it's intolerance for what sells for gas these days. Nothing I tried prevented carbs from fouling (changed to nylon main jets, but pilots jets are non-removeable type) and I tried several types of additives. Its always the pilot jets reacting and plugging due to the gas sold here, our boutique formulation we are forced to buy.
My biggest prob and disappointment with it now looking to put it back on the road is the instrumentation - the needles don't move anymore, something that started as an intermittent prob when I was still riding it, I would have to ride a few miles and then the needles would 'come back'. They didn't the last time I rode it and it was for long enough that they should have been back.
I don't know if this is a widespread prob or not, but if one you're looking at is not running, you may have to deal with the same issue. I don't know whether the gauges are still available or not, but they'd be expensive if they were.