The only time I feel that it's necessary to shim the rocker shaft stands up is when I'm converting a 54/55 cylinder head to the same compression ratio as an 848 head. That involves milling the early head .090" and recessing the intake valves the same distance. Moving the rocker shaft up avoids running out of adjustment on the rocker arm adjusters or installing shorter pushrods. The lash caps on the exhaust valve tips keep the geometry right when the shaft is raised. They also give the rocker arm tip a wider surface to contact as it sweeps across the valve stem. On a low RPM stovebolt engine with a fairly conservative camshaft profile, the rocker geometry is pretty forgiving. A high RPM racing V8 with a radical cam is a whole different bucket of snakes! I've spent lots of hours tweaking rocker geometry on some of the round track engines I used to build!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!