I'd also be concerned about the hours on the generator not having ENOUGH if they only used it 1-2 times per year. There should be a MINIMUM of 230 hours on the generator (that's only 12 hours per year, 460 hours is better). You want the hours to keep the moisture out of the windings of the generator and also to help minimize varnish in the carb on the engine.
If they don't have the hours, you'll want to get a good mechanic to look over the generator to make sure the engine and generator are in good working order. That's a $3-4k replacement if it's not in good shape for a new one.
I'd also just plan on a major service for the chassis with all oil, brake fluid and coolant replacements, especially if there are not very many service records. That stuff does degrade with limited use or even just sitting.