I have done a couple Boyds stocks, they do require some fit and all finish but can be done. As to the current stock, I would mortise and tenon a new forend onto it and depending on the severity of the crack, repair that too. Your weapon appears to be shortened at the best spot to add a replacement forend, some color matching of old wood and new and they work just fine.
As to the "bluing" Krags were hot oil quenched finish for the most part, so I would suggest you just keep the weapon oiled well and let the age and metal patina be your finish.
Just a couple thoughts.