It looks legit to me. From the dimple on the right side and where the Waffenamts proofs are, it appears to be a real 640b. If the grips are original to the gun it was made after 1942 (holster stamp seems to confirm that)
Real nice package! Neat to find it all together matching like that.
The last one I have seen for sale was 3 years ago. It was all matching #'s no spare mag and no holster. I believe it sold for $700ish. I don't follow them so that might not be a realistic price now days.
They made something around 300,000 of them.
Do you have any paperwork proving it was a bring back? Or did he just toss it in his duffel bag?
If you don't mind my asking, how much did you pay for it?
If God loved Christians as much as He loves geckos, He would have given them the ability to regenerate.