The rocker arms and shafts will bolt on and fit properly, clear back to ones used on 216, 235, and 261 engines from the early 1940s, through the early 1960s. Different arrangements will need to be made for proper oiling, depending on the year of manufacture of the engine, and some cylinder heads.
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!