I'd vote for replacing the tank, lines, hoses, and pump with new. Install a new filter inline also and think about a shut off valve if mounted low. After 50+ years its time and a whole lot less frustrating for the few $ more you will spend.
Bruce Old Toy: Ol' Betsy stock 59 Apache SB Stepside (Gone but not Forgotten) New Toy: 1962 Impala SS Coupe The Driver: 1990 Toyota truck