All of the new cams for stovebolts that I'm aware of are cast iron- - - -not forged steel like the 216 and early 235 engines ran. They require a different alloy of lifter, like Jay mentioned. Even the Melling CCS-12 which is sized for the 216 engine has a cast iron core, and it requires the later model lifter alloy.
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!