Opinions on possible USMC Springfield Model 1903

[Warthog]

Hello, this is my first post, so please go easy. I recently acquired a Springfield Model 1903 rifle with some interesting features. After doing some research, primarily using this site as well as others, some of these features seemed to indicate the possibility that it could be USMC.
According to serial number (852526), this rifle was originally manufactured at Springfield Armory in 1918. It has been parkerized and re-barreled (SA 7-27) at some point, likely around the date of the barrel.
Interesting Features:
1.) Punch mark by serial number (possibly applied by the Philadelphia Repair Depot when the rifle was rebuilt)
2.) Serial number etched on bolt, matches receiver
3.) Lack of markings on stock
4.) Vise marks on barrel
5.) “Hatcher” hole in receiver
6.) Enlarged gas hole in bolt

What it doesn’t have:
1.) Stippled butt plate (has checkered RIA butt plate), should originally been smooth
2.) 1940 or 1942 dated USMC Sedgley barrel
Questions:
1.) With the above features could this be a USMC 1903?
2.) If so, any way to know when was it acquired by the Marines?
3.) Would someone be able to check an updated SRS database for any hits? I have an old one and there’s nothing even close to it…
4.) Is there anything noteworthy about the sights? I haven’t been able to find much information on those.
5.) Any way to know original month of manufacture, or does one have to extrapolate? According to Canfield’s “Illustrated Guide to the ’03 Springfield Service Rifle”, a lot of changes were made around this time which could help validate some parts/finishes.
6.) Straight stock marked with finger grooves, ‘S’ on tip with one screw, trap cut for spare parts container, a ‘C’ or ‘G’ under butt plate. Does the stock pre-date the rifle? (second screws were supposedly added before 1918)
7.) Bolt is a C8, some research suggests this is a DHT straight handle? Could this be original to the rifle or added later?
8.) Very late in 1918, Parkerizing was introduced, but it supposedly had a blackish tint. This one has later pale green Parkerizing. Could it have been done as early as the late ‘20s rebuild, or would it have been in the WW2 timeframe?

Thanks in advance for all information, sorry this is longwinded. Please let me know if additional pics are needed… Tom