If I were replacing the doors, I would only replace the doors themselves as the early 50’s construction used one piece jambs with trim nailed on. the jambs were formed from a single piece of wood on a shaper, not the 2 pieces as the cased doors sold at the home centers for replacements and new construction are made. use the old door as a pattern for the placement of the hinges and the lockset on each individual door as the hinge mortises and lockset bores were marked and done on site at door installation time.
JMHO
Carl
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