(Below) Shown on the left are the removed camshaft components. The shims are available at my local dealer in a variety of thicknesses. I picked up two 2.000 mm shims which put both valves right in spec. $12.00.
One can see why valve checks cost so much as a service item. There's a fair amount of labor involved getting to the valves, removing cams, and buttoning it all back up. Though not strictly necessary, I remove the carbs and radiator, giving much more room to do this right. It's very important to follow the book on this procedure, lest the cam timing gets screwed up. Keep it clean and torque to spec. This adjustment should be good for at least another 30K miles.
The expansion tank, shown in the right photo, is actually empty. That gray tint is dirty sludge left behind from years of neglect. The tank is easily removed for occasional cleaning — I use a baby bottle brush and degreaser.
With the forks removed, the steering head bearings can be checked by moving the steering head back and forth, feeling for roughness or a "notch" in the centered position. This bike had a distinct notch, so I fitted an All Balls tapered bearing kit.
Flushing every two to three years will keep this from happening.