Plastigauge is OK for a quick check on a production engine. I haven't yet found a plastic ribbon I can read to the 4th. decimal place, or even close. My dial bore gauges read out to the 4th. digit, ditto on my mikes, and I check them repeatedly with standards during the job. I don't have any argument with people who accept more tolerance than I do- - - -they are better able to determine what their work is worth, or what's acceptable to them. 50 years in the trade has made me a little bit picky.
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!