This is confusing. McMillian Fiberglass Stocks only makes fiberglass stocks, as used on the M40A1 (1980s-90s era) thru M40A6 (201X era)
A pre-64 Winchester Model 70 is generally a wooden stocked rifle, so don't know why a McMillan stock would be a consideration if a "replica" of of a USMC sniper is the goal - esp an M40A1. Here's three USMC replicas representing different eras: M40 in 308W (circa 1967 to late 1970s), the M70 in 30-06 (circa early Vietnam war 1965-1966), and the M1903 w/ 8x scope circa late WWII and Korean war (1943 to 1953 era).
I think you need to set you goal as to what platform and caliber that you want (Winchester M70 vs Remington M700, 308W vs 30-06), and then set your budget as the price of scopes can vary widely based on how "correct" you want it to be. Only then can you decide what you really want, but if I had an extra pre-64 M70 - I'd build something like I did with that middle rifle, which started life as a mid-1950s Featherweight in 308, but reborn in 30-06 as a hybrid USMC M70 sniper circa mid-1960s. (The 12X Lyman scope has since been replaced with a 1960s era Unertl 10x). Just remember that a replica of the M40A1 is a very expensive journey - assuming something reasonably "correct" is the goal, and that would require an M700 short action, not the pre-64 M70 that you have.
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Here is a well-known picture of Carlos Hathcock with his retirement gift from the USMC PWS shop. It was a post-64 Winchester Model 70 with a heavy barrel, an early McMillan stock, and a vintage green anodized Leupold 3-9x scope from the Vietnam era. This rifle/configuration was never used by the USMC, but Hathcock liked the M70s and the then new McMillan stocks, so that's what the PWS gunsmiths made for his retirement in 1979.
