I am guessingthat is a byf made by mauser. I have one made in 42 with all matching numbers (except for the magazine) that is in mint condition. It is aWWII vet bring backandit appraised for $1500 whenI inherited it 8 years ago. I would guess that it would be worth close to $2K now.

IfI were youI would make the swap before the dude changes his mind!