The Singer 251-12 is not a walking foot machine. It is a drop feed only machine, and it does not have reverse. I'm thinking it was more of a clothing machine.
What you need is a single needle, lock stitch, compound feed, walking foot machine preferably with reverse, but that is a luxury, not a necessity. That would be a Singer 111W, Consew 226, Pfaff 1245, etc. I would pass on the 251.
No one lives forever, the trick is creating something that will.