I'm pretty sure the "lifter" in the pic fits the Pontiac overhead cam 6-cylinder used in some versions of the early Firebird. It's based on the 230 cubic inch Chevy 6 with an overhead cam cylinder head, I believe.

"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!