I understand that "exact" is the object.
However, Barton makes some really $$$ rocker arms for the Gen-2 Chrysler 426 hemi engine, which have some side-scrubbing of the rocker roller on the stem tip as the valve opens (the rocker's oscillation path isn't in the same plane as the valve stem and guide). This is apparently insignificant, even in these high power, high RPM, high spring load engines.
