well I have only seen one speared through rocker on a sb mopar in my time, but I have seen numerous speared through big block rocker arms.
The reason for a roller tip when valve lift exceeds .500-.520'ish there is more side loading/scrubbing of the valve tip which will accellerate or cause pre mature wear on the guide, also at a point the non roller will wipe across and off of the edge of the valve stem, which where lash caps come into play when guys used to run circle track with the old 273 rockers.
The other reason for adjustables is pre load, or you could have various length push rods to really get it right, or adjustable push rods throughout, but usually when the accuracy becomes that important, the lift increases and the roller requirement comes onto play.O and when ya have a solid cam...ya kinda need'emlol
No matter, thats why there is a relm of preload in which it'll run and ya probably won't feel the diff if it's .020 off one way or the other
I'm sure there are other reasons
