It is unlikely...
that the re-chambering to .32WS can be reversed using the original barrel, because the new chamber is considerably 'fatter' in the body and shoulder than the straight-tapered .32-40.
The problem is aggravated by the need to set-back the barrel far enough to permit re-chambering to the original caliber, while retaining enough of the enlarged breech area ahead of the takedown extension to shoulder firmly against the extension, and permit re-threading and machining the barrel shank and the interrupted-thread takedown shank.
A new barrel would likely be required, and an original of the correct type and caliber is almost certainly not to be found in shooting condition.
On the other hand, the rifling pitch and groove diameter should be correct for the .32WS, which is a better hunting round.
If the rifle shoots accurately as-is, I'd leave it alone.
PRD1 - mhb - Mike