If it has 16.5" wheels, I'd replace them with 16" wheels. Since you have a bunch of new tires, I'm kind of guessing it doesn't have the 16.5" wheels as 16.5" tires are getting pretty hard to find.
Otherwise, there's not much chassis related I can think of beyond usual old vehicle stuff: make sure the brakes are in good shape and operating freely, change fluids if they're at all questionable, check belts and hoses and spark plug wires and distributor bits, that sort of thing. (Note that my inability to think of stuff doesn't mean stuff doesn't exist that would be good to do!)
For the house part, if the converter is original or even comparatively old, replacing it with a modern multi-stage converter would be well worth doing, and probably doing fairly soon. There haven't been as many improvements in most of the other appliances and stuff over the years.