Looking at the photos makes me think that a previous owner attempted to nail/screw on a shop made handle of some sort. That, and your modification, are examples of the many changes that who-knows-how-many previous owners make to old tools. I normally try to keep the ones that I do to a minimum, and when I do make them, I use traditional modifications and/or corrections aimed at keeping the tools in proper performance. A good example would be patching the sole of a worn wooden plane to close up the mouth. If an old tool is a truly rare and unique example then it should be left as-is. If, however, the tool is a common one then it becomes a “canvas” for the expression of the owner/user.
Have fun with it,