Kudos for O/P's quesiton here! Plus 1 to the above comments! Adding small dimension. Respecting rare chamberings and/or configurations. Mix & match not unusual and if competently done, never to know... Reasonably undetectable!
War story: Latter sixties, finding a prewar Model 70 .257 Roberts, short rifle, 20" barrel. Some couple hundred dollars even then as action swiss-cheesed with mount holes. Friend, advanced collector/home gunsmith. Few years later, swapping actions for me with my well used early postwar Win .257. Headspace-on as skilled chambering reamer kiss + sixpack! Results, competent & never reasonably to exhibit any difference! Realistically assessable as early postwar factory "barrel cleanup". Eventually sold to same long begging friend. My decent profit, likely his estate windfall.
Such as barrel swaps: Sight indexing to vertical and headspace, both critical 'tests'. And no, George... No "ultra-rare custom shop editions" for cross-eyed southpaws with vertigo!
Basic knowledge, critical eye and 'sniff' test... "Rarity" or other $$$ providing motive'!
Best & Stay Safe!
John
