All flat-tappet valve lifters have a slight convex radius, regardless of the vehicle manufacturer. Flat or concave bottom lifters are worn out.

My Black & Decker valve grinder has a fixture for reshaping the radius on rocker arm tips, but I don't recall seeing a similar fixture for regrinding lifters. I use a tool post grinder on a lathe to do that.
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!