If it does not have center side mounts it is pre 1958.
Before 1958 only engines that had Power Glide transmissions, had hydraulic lifters. Stick cars and truck engines are not drilled to supply oil to hydraulic lifters.
Starting in 1958 all 235s are drilled for hydraulic lifters, whether they were used or not. This was done as part of the new oiling system for the rockers. See Fig.#15 in this
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