Early 265's had a flat spot on the distributor housing. If it was not clocked properly oil to one cylinder bank would be restricted and the lifters would get noisy on one side only. That problem was corrected about 1958 or so buy putting a groove all the way around the distributor instead of a flat spot. On race engines with solid lifter cams we used to put restrictors into the side oil galleries to prevent filling the valve covers with oil from a high-volume oil pump. That also kept more oil going to the crankshaft through the center gallery.
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!