Front Drum Brakes
Set them up carefully and make sure they’re clean. Run the vents closed unless you are having a problem with brake fade. New cables regularly will save you from trying to set up these brakes with sticky cables. This is impossible, by the way. Sticky cables also lead to sore wrists and finger from the monster pull needed on the lever to get the brakes to work.
Radiator
These radiators are nearly 30 years old. Take them to a reputable radiator shop and have yours cleaned. Your bike will love you for it.
Cooling system
Apparently, if the water pump fails, you can replace it with the engine still in the frame. Consult the magazine Classic and Motorcycle Mechanics or any of the Waterbuffalo or Kettle resource web pages. Thermostats do fail and can lead to big problems. Replace those hoses as well.
Ignition
Once again, electric is better than breaker point. There are no bolt-on kits, but apparently the one for 3 cylinder two stroke Kawasaki bikes can be made to fit with a little modification.
Pipes
Tend your baffles or they will go away. This is a current problem with my ’72 and I’ve looked for a number of years for a replacement. This is the spring that I do SOMETHING to get this bike quieted down so I can use it on the street again.