Guy I was working for as a teen rebuilt a 265 for a customer's '55 pick up, got it running and no oil to the L.H. (as I recall) lifters / rockers. He called an old machinist friend who told him " look at the old cam, should have a flat on rear brg journal, take the new cam to the grinder & grind a flat on the the rear onto the new cam to match the o.e. one." Seems early production V8 didn't have a drilled passage to feed oil the lifters on that bank, oil flowed via the cam flat. I've never seen such a thing again.
