There are the old radio guys who seem to hoard NOS caps.
You may want to check these guys to see if they have something that
might fit:
https://www.vivatubes.com/
https://www.justradios.com/
Personally, rather than depend on the condition of a very old
electrolytic, I'd probably rebuild "in the can" with modern stuff.
Unless you're taking about paper-in-oil caps, I wouldn't be very
sanguine about really old stock--they have a tendency to dry out even in
storage.
--Chuck