Bing–This was a common problem with quite a few engines of this time period. The oil passages to the rocker arms would sludge up. This was true of the Ford V-8 and 6 and the Chevrolet 6 engines of the 1950s. Outside oil lines were available that bypassed the internal passages. It wasn’t the lifters that would become noisy, but the rocker arms.
I had a 1955 Pontiac that had the problem of oil not getting to the rocker arms. This engine did not have a rocker arm shaft, but had stud mounted rocker arms. No outside oiling kit was available for this engine. The engine had been overhauled by the dealer before I bought the car, but the problem persisted. The oil filter was an option on the car even though it had hydraulic lifters. My Pontiac did not have the oil filter. I did purchase the oil filter assembly from a salvage yard and fitted it to the Pontiac, but even pulling the studs and cleaning the passages as well as changing the oil frequently never really cleared up the problem.
I had the same problem on my 1965 Rambler even though I faithfully changed the oil. An independent shop pulled the cylinder head and cleaned out the passage to the rocker arms. Apparently there was a bend in the passage in the block that was prone to collecting sludge. The total cost of that repair back in the early 1970s was under $40 and that included the head gasket. Can you imagine what the price would be today?