I would agree, and I would expect this to be due in part to the fact that the M39 uses a S&B scope that is very hard (but not impossible) to source as a civilian.
Didn't Choate make the original butt pad?
On my Mk14 clone, I've gotten as close as possible to the original without losing my mind (or draining my bank account). I use the modern butt pad, the black EBR rings (I'd buy the grey if I could find them), and a Sadlak spring guide. I also use a SEI barrel and trigger components. If I switched to a SEI scope mount/rings, I'd actually be pretty damn close to the SEI Mk14 USAF rebuild. My bolt is also not engraved, but I would have it done if someone offered a reliable and accurate service for it. I have absolutely no desire to pick up a 1 in 25 stock...
As far as people not knowing what it is - I've actually had two guys at my club come up and ask if it was a Mk 14 (one of which was shooting a brand-new SR-25). I had the 22" barrel at the time, so I'd say the NSG stock is the most identifiable portion of the gun; no one will notice an incorrect grip but yourself, and people on this board.