I wouldn't count on them fitting any other Westley Richards doubles without a serious amount of adjustment. Also each of the Westley rifles and shotguns are on scaled actions so the only double they would have any chance of fitting would be one of the same calibre that they originally came from.
Pugwash thanks for the info re the scaling. These are from a defunct single selective trigger 12g made in 1904. The gun was badly mistreated before it came to me (burst right bbl, cracked knuckle rewelded). It is beyond salvage an I fear if sold whole someone might try to cobble it together.
It was nice to display and admire as a stripped action but our laws now impose keeping even inoperative parts in a safe. So no more display!