Don't refinish it, reblue it, or anything like that. It will be more valuable as-is, despite the fact that it's beat-up and the numbers don't match.
FWIW it's common for Mosin-Nagants to have non-matching numbers, or renumbered parts that have had the old serial numbers lined out and the correct serial number engraved or stamped in their place. These rifles led harsh lives and most of them are "parts guns" to some extent. Furthermore, if the bringback theory is correct, the Soviets wouldn't have cared if the bolt blew back in the face of some Southeast Asian peasant.
