Rough idle issue

Trying to diagnose rough idle on new engine. New HEI ignition, tested wires, NGK ZFR5N plugs, Weber 38 adjusted to best lean idle and timing at initial +15 degrees. Also snugged down all intake bolts and does not appear to have any leaks. Runs and accelerates great but stumbles a bit when idling. Really bad in gear.

Has a Oregon 2106 cam, adjusted lash to .015 IN/EX per cam card while on the stand. Maybe too tight? Other thoughts?
When you say you did this "on stand"?..
Was this on a engine stand or an engine run stand? As in did you do it while the engine was hot? Because that's what your cam card is calling for when the engine is hot and yes it changes...
What does an Oregon 2016 cam specs consist of? So I don't have to go find it I assume this is a slant six?...