I found taller top nuts for a threaded headset, 20 years ago.
some improved support. if on the upper end of adjustment range.
But, it is still best to have the wedge of the quill stem
below the portion of the steerer that the threads are cut from.
Nitto Technomic , is a popular long quill stem , currently made.
now if the fork is left long enough that the locknut bottoms out on the end of the fork steerer,
before making contact, with the top of the adjustable bearing race of the headset,
so it wont stay in adjustment, then you add a spacer between the two.
What are the structural and practical implications of changing the std. 2mm spacer for a bigger one in a 1" threaded headset? Would that effectively raise the bar hgt. by leaving more of the steerer in place?
you wont get the lock nut on top to engage enough , if any threads on the steerer ,
then the headset will stay too loose.