You posted a T54X engine code suffix.
1954 3100 (1/2 ton) truck engine assembled in Tonawanda, NY
By the way, I have had many 1954 engines with original, slotted, valve covers and I have never had rusting on the under-side of the valve cover. I also made sure that all my engines had oil feed to the rocker arm assembly, resulting in oil sloshing inside the valve cover.
People have reported water leaking onto the engine through the hood (I have never seen that). If I observed that, I might consider sealing the slots/slits in the valve cover or using a newer valve cover (and then using a breather oil filler cap).
