The 700+ HP MOPAR 440 truck pull engines I built for several years back in the late 1990s used needle bearing roller rocker arms on OEM shafts that ran the full length of the cylinder heads, with triple valve springs and a roller cam. Seat pressure on the valves was in the 300+ pound range and we ran them 7K+ RPM. Those roller rockers used simple close-fitting flat washers at each end of the roller bearing to retain the oil. I don't recall having any oiling problems or shaft failures.
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!