The rocker shafts and rocker arms have been pretty consistently the same size- - - -216 through 261. The oil grooves in the rockers changed location in the late 1950s when the shaft oiling system got reworked. Somebody is selling replica shafts on Ebay, but the supply is somewhat intermittent, and I wonder if they are getting the same kind of heat treat as the OEM shafts?
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!