In the early 1973 to the mid 1977 I race a 426 street Hemi in NHRA stock in division 7, SO CA,, I bought a bunch of blowned up street motors and ended up checking around six sets of stock rocker arms on one side of one motor with checking springs, I set the lash at zero and use the same cam and solid lifters on all the rocker arms sets. I saw from .030 to .140 lift differences at the retainers on the intake rocker arms and more lift differences on the exhaust rocker arms .
I was able to get all the lifts within .015 of each other at max lift at the valves .
I hadn't heard of anyone back then fixing and blue printing those rocker arms, that happen a little later at the end of the 1970s