That's a pre-'66 bolt. The bolt heads were different and have been obsolete for many decades. Not only is the bolt head different, so is the bolt body. The crosspin hole is 90 degrees off from current production, not to mention a different length. Chances of finding one is pretty slim. I think your only hope is have a bolt made using current parts, but it will also have to have the barrel tennon trimmed back and re head spaced. The standing ejector will have to be removed for the bolt to work.
I guess your "bargain" may have more than you bargained for....