Since the rocker shafts only wear on the bottom, it's possible to turn them upside down, drill new oil holes with a solid carbide drill bit, and plug the holes on top with pieces of round brass rod. Clamp a slightly oversize piece of brass into a drill press chuck, and file a slight taper to make a short plug that can be hammered into the top of the shaft. "Rinse and repeat" for all the top holes so the oil only goes to the bottom of the recycled shaft. Those shafts are harder than woodpecker lips, so filing on them is a lost cause!

"Worn out" rockers are excellent candidates for the conversion I do to Torrington roller bearings- - - - -ditto for those worn shafts, since I grind them down to fit an 18MM diameter bearing. Anyone who has rockers and/or shafts they're replacing, please don't discard them!
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!