The rebuilder I worked with in Nashville bought a balance machine specifically to check those cranks- - - -the balance was definitely different between cranks from 305's and 350's, and there was an annoying vibration problem if one from the wrong engine got swapped by mistake. Producing about 200 rebuilt engines a week will teach ya a few things about "matching part numbers".
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!