That peep sight is really unique! According to Jon Speed he has never seen this arrangement before. It is completely different from the detachable peep sight offered for the Range Rifle many years later. At that time, 1908, Mauser still experimented with a lot of factory options like scope mounts to test the market. Despite the shortened barrel the rifle with the peep sight and the 3/4 length foreend is IMHO a very rare and collectible example of a pre-WW1 commercial Mauser! I hope your gunsmith can do a good job restoring the finish, but you both should avoid to make a "new" rifle from this piece of history. Congratulations!