Definitely go with the Wing, and even then you may be overloading it. The Wing will take the overloading much better than the CB650. I have owned both. Good heavy duty tires and aftermarket rear shocks will be essential.
Servicing the carbs on the old Wings is a PITA because access isn't easy, but once you get them right they will stay right until you park the bike for a long period of time with old gas in it. An experienced old Wing rider will be able to tell if the carbs are right by taking a short test ride. Replace the points ignition with a Dynatech electronic ignition and you won't ever have to service that part again.