To figure the situation with the enlarged holes out, I posted my conundrum on an online builders group. some of the suggestions were to go to a longer rivet and set the rivet slowly to allow the material to fill the enlarged hole. Use an oops rivet (NAS1097), and finally to simply upsize the affected holes to 4-4 rivets. I elected to drill out the holes with a #30 drill and re-dimple the new holes with a #30 dimple die, thereby enlarging the holes to take AN426AD4-4 rivets. I then marked five rivets for installation when these pieces are finally riveted together.
I then moved on to installing the nut plates to the E-615PP Reinforcement plate. I was able to set the rivets using the hand squeezer and complete work on the part.