I would flush the entire coolant system because of the age, then be sure to replace with your favorite flavor of coolant and water. While at the task you might as well do the boiling water diagnostic check on the thermostat. I would also find out what the open and closed current is supposed to be on the sensors and check them as well.
If they aren't expensive forget about checking the sensors and just replace the things for a peace of mind. I'd do the same with the thermostat.
Once you have the bike running and up to temp grab the hoses and see if there is pressure building up. I doubt you have a water pump problem by your description, but it's worth a look.