I can’t think of a single time the shaft needed to be lower. Ever. That would mean the valve tip is less than OE and the lift is much less than OE. So that makes zero sense.
Rocker design and tip, lift, stem height all affect geometry. If you are grinding on a rocker you have geometry issues. Fix that and leave the rockers alone.
Again, since you are carrying the flag for beehive springs (which aren’t new BTW) I’ll ask you again. How does going to a beehive spring correct bad geometry?
