Update: cam followers
Here's an update. I inspected the rockers last weekend. I replaced the rollers last in late 2001 and have inspected at 60, 100 and 120 hours.
This year I have been bad and have not even adjusted the valves all year. So, with approox 140 hours the rollers have a barely perceptible slop in the intake rocker, some roughness in both rollers, and the rocker shafts are visibly worn (I rotate with each inspection).
So...updated to new rockers and new shafts. Should be good for a couple of years more I figure!