I'll switch sides now. Lots of anecdotal evidence of adjustable sights being installed on existing carbines during WWII. Besides the many anecdotes I have seen a document that shows the North Africa Theater (NATO - later to become MTO) in February '44 wanted to replace rear sights on a couple of hundred thousand carbines in their command. That obviously didn't happen, at least not in those quantities, but the point is the documentation still turns up to make us reconsider some opinions. It would be no embarrassment if a wartime sight replacement was performed on yours. For that matter, this WWII rear sight scenario could explain the handguard and bolt as well.
The transfer marks from metal to wood is good evidence, but it doesn't mean it didn't happen in civilian hands after stock replacment. 66 years is a long time. And Brophy is the author of a book on the '03 Springfield. He not only researched the period, he lived it. While his book pictures many arsenal rebuild stamps, the AAOH is only sketched, so we can't compare font. We still know very little about the postwar rebuild activities. I have an 03A3 with a Benecia Arsenal rebuild stamp on it (though with no doubt about it being a rebuild). That's kind of unusual too, so I understand the mental gymnastics involved in seeking info on an arsenal that didn't do alot of work on a particular type of weapon.