I thought that I should write up "the rest of the story", in case anyone in the future reads this saga when they are facing the same issues that Harry did.
The treatment plan worked beautifully. No further surgery was needed. The infection was cured and the hole in Harry's mouth closed up. He was discharged from the oral surgeon's care in late March, with a follow up in 6 months. He no longer takes any pain medication (a little tough for several days while he got off the pain meds).
There is no visible scar on his neck. His jaw looks perfectly normal. You could never tell by looking at him that a bone is missing and there is an implant in there. The hyperbaric treatments took care of the wrinkles on his face, so at age 81, he now has a fully smooth face! The VA doctor commented on his wrinkle free face just today. He has regained all of the weight he lost (15 pounds). He has great energy and no pain. He looks better than he has in years and feels better too!
Eating is still a problem, so he continues with feedings via peg tube, while trying to eat some food by mouth.
We have started to travel again and have a full summer travel schedule planned. We just got back from a week in Ireland (taking his Ensure with us). Had a great time. Harry's plan is to keep going as far and as fast as he can, as long as he is able to go. He advises all his friends to do the same.
We are very pleased with the final result of this surgery and wish equally good luck to others who have to go through this ordeal!