WWII refurb - look on left side of stock - I have one here stamped "AAQ" - is apparently the stamp for Augusta (Georgia) Arsenal rebuild - there were numerous US arsenals doing refurbs in WWII. Can't provide a reference, but I was under impression that a WWII re-furb would have the stock stamped to ID the arsenal that did the refurb. Your finish looks very "fresh" - WWII parkerizing was dark or grey, I believe - became greenish coloured with years of dirt, gun oils, handling, etc. Have read several discussions of "authenticating" these "re-builds" - gets into finding matching dings / scratch marks crossing from wood to metal bits, from wood pieces to partner wood pieces, etc. FYI - just was reading a 1963 Guns magazine on Internet - ad from a Chicago store selling M1917 - Eddystones were $29.99; Remington or Winchester were $34.99. Very good reference books for you are "Pattern 1914 and U.S. Model of 1917" by Charles Stratton; "United States Rifle Model of 1917" by C.S. Ferris. I got both from Amazon within past year or so.
As far as mixed parts - probably some of that going on in WWI? Did not find a lot of references where these rifles used much by USA after that - even WWII re-furbs - not certain many or most were even issued for overseas combat duty?? If you go to m1903.com website, down left side to "M1917 Parts" - end up with chart / list of parts - click on part name - line drawing pops up showing where each maker made their mark on each piece. Not the same. Good evidence of "games" played over the years - I have an M1917 front band with "W", "E" and something unreadable where the "R" is supposed to be, all in correct (different) locations; all on the same part. Also have "re-finished" parts that a "DP" visible when held in correct light.
As per those reference books, most M1917 parts were stamped with a US acceptance mark - an eagle head,with a tiny number behind it - Ferris book lists which numbers went with which manufacturer facilities. Have received many P14's with eagle head marked parts - the parts are physically identical and work perfectly - just the eagle head says that part is for the M1917, not a P14. Many parts in M1917's without marks that should have had the eagle head - so, missed in production or could as easy be P14 parts, in some cases. Certain parts absolutely not interchangeable - bolt stop boxes for example. But sears, safeties, triggers, bands, etc. much harder to tell one from the other... Trigger guards and floor plates can be "made to work" but were not the same to each other; same with the stocks and hand guards - can be "made to work" but were not originally the same.