With the proper setup in a lathe or a milling machine, it would probably be possible to bore the rockers out, press in bushings, and ream or hone them to fit the shafts. "Drilling" would probably ruin them. You'd have more labor time invested than it would be worth to try to save a worn-out part. Those rockers aren't scarce enough to justify heroic rebuilding efforts.
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!