Wow. I won't presume to add a contribution to the Parker side of the equation in this august company other than to say it is a beautiful gun!
You did however ask about the value with association to a former owner or event and David weighed in on that point and, as I can contribute on this aspect in this case, I would comment as well.
You have made a good dollar investment in a Parker. You have made a great dollar investment in baseball memorabilia. This combines to create a SUPERB investment.
The issue is not that your gun may not have all the original bits and the barrels aren't the original Bernard, (the lug has a 2 marked I think used to denote a second barrel set?), and whether current barrels are true Titanic or Vulcan re-roll marked, - (both legitimately expanding your shooting options over the original Bernard), and that the stock is now straight versus pistol grip in the letter, or even the issue of amount of refinish - lovely done by the way - versus original finish. Indeed all of which, and this was referenced already by another member, can be reasonably explained by the active use of the gun over time.
All the above would be very significant, in fact be the most significant, aspect of the gun's value even greater perhaps than present condition of the gun -
IF not for the association with the World's Fair
and Christy Mathewson. This is where I transition away from the emphasis of value from the comments thus far.
A CH grade gun will always carry an intrinsic value and it will always have it's devoted (me too!) admirers. However CH grades are not exceedingly rare.
A documented World's Fair gun is a much rarer bird and a documented gun associated with one of the immortals of baseball - and their were few if any players ever more loved and admired than Christy Mathewson, is in a category of it's own.
Fast history: Not only was he an exceptionally skilled ball player (13 out of 14 years he won 20+ games and had 4 seasons over 30+ games - he was a literal GIANT of the game - pun intended!) he was also a true gentlemen and genuine American hero. "
He gripped the imagination of a country that held a hundred million people and held this grip with a firmer hold than any man of his day or time" per Grantland Rice the famous sportswriter of the era.
I have no idea what you paid for your gun, nor do I desire to as I would probably cry like a baby with envy, but I can assure you that,
since it has iron clad provenance to Christy, if it is worth '$X' as a Parker in present condition and value as a World's Fair gun, to a Mathewson collector it is
at least 50% more.
Frankly I am only started with 50% as that small, churlish, bit deep inside of me hopes I could persuade you to part with it!
To me, and I am only a generalist when it comes to Mathewson and this is the part where I may get the other members thinking I'm nuts,

, I would much, much, rather own Christy Mathewson's C gun then any non-provenance A. You have a collector's dream - an item that crosses multiple markets.
My warmest congratulations. Enjoy! Cheers JG