Those are the so called "single nut lifters."
"Multi-nut" lifters have a "locknut" besides the hex you adjust on the top - which according to my engine rebuild from 40 years ago IS a way to go, but not the best.
The problem with multi-nut is that the act of tightening the keeper nut, it throws the adjustment out of whack. You can put MANY hours trying to get that elusive gap - and when you're done they're no more reliable than a single nut lifter as locknuts DO come unlocked.
Single nuts STAY - well, they should. They're designed to STAY first time as there is a gookem-pucky inside which pulls a "Loctite" on the nut once set.
I went with my rebuilder's advice and used the single locks. No problems looking back over 40 years.
And yes, you can use them with split guides.
Joe K