Definitelly a missed lifter of the bore will drop the oil pressure BTDT. We can't say the missed pushrod will mean a lifter out of the bore ( I have bent some pushrods being out of its place and lifter still kept in place ), but it could be.
With a new oil pump, definitelly needs to pack up the pump rotors with grease or oil, but if it was already running, is not necesary
With a Charger born in Chrysler assembly plant in Valencia, Venezuela