That's not a bad price nowadays on an original M375, and it is true that you don't often see an example for sale. And yes, if the stocks are original; they would indeed be American black walnut. As FYI, new Marlin rifles from that period came out of the box with a sticker on the forearm that stated "Genuine Walnut" to remind rifle buyers of the quality materials and old world craftsmanship Marlin still built into their rifles when other makers were transitioning to stained hardwood stocks. I live in GA, so long shots on game are uncommon, given our thick woodlands and swamps; but the longest shot I've ever made with a Marlin was with my M375 at just over 175 yards. Unlike you, I had to make my shot with the aid of a scope; but there is no doubt that a 375 Marlin will reach out and touch a game animal if you do your part. Good luck.