Replace or re-arch rear leaf springs?

rearch is a bandaid. those springs are 59 years old. how much life do ya think that metal has left.

put new springs on the thing. call espo ( Spring and Suspension Specialists | ESPO Springs n Things ) or eaton ( EATON Detroit Spring ) and get some stock replacements and be done with it. you'll be happier in the end.

you may or may not see them on the actual web site so call them and talk to someone.