Discrepancies in information on LA and Magnum series oil gallery plugs

Unfortunately you are dead wrong. The driver side galley is indeed pressure fed, that's what supplies oil pressure to the lifters. And that threaded plug goes in from the rear, not the front.
Sorry wrong end of the engine was thinking it was front dist. location like B/RB not small block like Chevys. Looking at the pictures it appears Chrysler used a sealer on the thrust plate to block something like permatex #1 paste to seal the plate. So using the plugs in the front galleys is the safest method and do as recomended about drill a hole in plug and use the factory slotted plate to lube the chain. The drilled bolt still only feeds oil by any leftover from the lifter chamber by splash collection.