Wow!
That is very cool. I've never even held an SVT-40, let alone a sniper, so take my comments with a grain of salt, but that looks as real as it gets. The patina on the scope with the wear marks from the lens caps, the round headed screws on the elevation and windage knobs, and the makers markings speak to a legitimate PU scope. Similarly for the scope mount. Does the ground and restamped serial number on the scope mount match any other number on the rifle? I don't know who put it together but it looks like all real parts. If the real experts agree that this is all authentic parts then, even as a complete mismatch, that has to be worth $2500+, right?
Oh, and that 1938 91/30 on a hex receiver...have you looked at the tang date? Laminate means post war refurb on such an old 91/30, but the hex with a 1930's barrel date is very nice/unusual.
You sir, have had a very, very good week