I am in the process of setting up a fixture on my lathe to resurface the bottom of flat tappet lifters. The most common radius is either 60" or 72". Once my fixture is up and running, I should be able to do both. The simplest way to duplicate some of this supposedly obsolete technology is to do it yourself- - - - -then you don't have to be at the mercy of the so-called "experts"! Anybody with the unmitigated gall to call himself a "machinist" should be able to figure out a simple procedure like grinding the bottom of a valve lifter to a specific radius- - - - -all it takes is a lathe and a tool post grinder!
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!