I won't address the stock question which has been answered, but I will address the sling question. It is likely fake. Why? All of the observed 1950s-60s era M1907 slings were
imprint stamped with a leather stamping die regarding the date of the MRT treatment. This lasted up until 1969. Beginning in 1970 one first sees the ink stamp used for MRT and its date. Here's a 4-63 USGI sling and you can see that it is imprint stamped,. This is a legit sling and have owned a few... (I might have a slight fetish for leather M1907 slings...my collection ranges in dates from 1917 to 2011 or so, with many in-between).
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It took me 4 years to finally purchase a serviceable 1970 dated M1907 sling for my replica XM21 rifle (see below), and this is the first year that the ink MRT stamping shows up on the slings. So 1970 is when the inked MRT stamp first appears, per a change in the US gov't drawing. All M1907 slings observed prior to this new marking are of the die-stamped variety. (I seem to recall from someone with access to gov't drawings, that Rock Island Arsenal maintained the drawing for the USGI M1907 leather slings, and the drawing has been periodically revised over the decades).
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As for this 1970 sling - I actually spotted it on gunbroker in 2023, and while the M1A rifle it was attached to didn't sell, I was able to talk the owner out of this sling for $100 shipped. Again, I have observed/hunted down MRT dated USGI slings for many years, and I don't think ink was allowed for the MRT dating back in 1962...Anyhow, forgive the digression over my sling obsession. (Honestly, I'd love to find a legit 1962 dated M1907 leather sling for my replica of a 1962 NM M14, but "4-63" is what I been finding instead over the past decade of observations. These USGI slings always made in batches).
Fwiw, the most commonly seen MRT date is 10-86, and that would be the proper era for that nice M40A1 stock in this thread. (See bottom sling)
(Runner up for "correctness" would be a 1995 or 96' dated sling, which is what I used for my 'late 1990s' replica M40A1 w/ take-off stock. My 2cts.)
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Lastly, here's how the green web slings were stamped back in early 1962, at least for the contractor who made them that year:
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