I’ve also finished the retrofit of the front vice face to take bench dogs. I cut a piece of thick scrap maple to size then screwed it to the existing face, then marked up the spots for the dog holes and drilled them. Once done, I tested it out with a couple of different sized pieces of wood and it worked great. Below, you can see the new piece being added to the existing front face. I used my trusty yankee screwdriver to do all the hard work!
Here I’ve marked the spots for the dog holes and used a nail to mark the center ready for them to be drilled
Here you can see the holes completed
and here it is in action, with two different sized pieces of wood and my newly made bench dogs in use.