[rotorwrench]

The hollow adjustable types are lighter weight and have less a tendency to want to keep moving up from their own mass/velocity under higher rpm conditions. This was the reason most folks specified the Johnson adjustable types back in the day. There were several other companies marketing them too but Johnson might have been the manufacturer of those.

It sounds like you are painted into a corner a bit with the late types. Wick & Lock type of Loctite or peening the edge of the thread bore might fix things. The best kind of tappet followers were the original hollow non-adjustable type.