Virtually a lock to be a '57.
Somewhere out there is a left-handed elk/moose/sheep/brown bear hunter who knows that the left-handed Fred Bear killed a world record Stone sheep with one of these. (Not sure on the length he used.) Find that person and you can name your price.
Otherwise, it will be a little tough to move it. My unsolicited advice would be to hold onto it until you actually find a committed buyer and not a vulture.