Nearly all the pre-1912 commercial Mauser Bs have the military style floorplate. If the tangent sight on your rifle were still present, you would see the purpose of that tiny flat on the barrel reinforce: It allows the tangent sight to be set in it's lowest, 100m position.
Good luck in finding an original, pre-1912 stock! These came with a round pistol grip, tapering, no Schnabel, foreend and half-oval, C-shaped side panels.
The buttlate shows the Simson, Suhl trademark instead of Mauser's then shield with intertwined WM. Otherwise it is very similar to the Mauser type. I agree with Lancaster, the stock does not look so bad from the photo. It still shows the original shape.