Brian, I like the idea of using wood filler.
I did finish boring the remaining three mortises today. And I decided that once I finish cleaning out the mortises from the underside of the top, I am going to go back and redo the mortises from the top side. I was in such a hurry to get the mortises done, that I didn’t do a good enough job on the top side, I need to fix that before moving on. I also decided to take off the tail vise and work on it. Where the vise attaches to the bench top, the metal vise is not a true 90 degrees. So I am going to do some grinding and fix that as well.