While I would personally have a hard time building a new gun to look old, you really nailed this one IMHO. The inevitable little nicks a stock would pick up over the years, the extremely well done metal finishing with a little surface rust in the right places, some buggered screw heads, etc.
I’ve built quite a few Milsurp kits and always tried to match the replacement parts finish to the original parts. It’s not easy to carry out in its entirety and make it convincing, your rifle is an outstanding example.