Calipers? Not likely. Maybe a micrometer that reads accurately to the 4th. decimal place, or possibly an optical comparator. The finish on lifter components is also important, similar to what's needed on Diesel fuel injector parts - - - -so smooth that high pressure fuel doesn't leak past mating surfaces of high-polished steel without any gaskets or seals involved.
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!