Last summer my 1982 Competition GS was returned to me with all the original parts I had on it. Took it out for a ride and entered a tank slapper at 35mph down hill. Controlled it and made it home. Put it in the stand and found spoke tension to be exceptionally low. Brought it up to tension and have been riding without a hitch. Hit 40mph the other day without trouble.
One trick I learned with motorcycles was to tighten down the tension on the headset. helps to stabilize shimmy's.