Opinions are like "noses" (and other body parts)- - - - -everybody's got one, and some smell better than others! As long as a lifter isn't concave, or has a rough surface where it touches the cam, does it really matter in any practical manner? Every brand new mushroom lifter I've ever checked with a machinist's square (several dozen) have been flat. How about some input from other people who actually do shop work?
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!