I don't think you can put any definite numbers on adenectomy regeneration. Too much depends on how the procedure is performed. Where did you get that particular figure?
I've worked with some of those television entertainers, and the snakes I planted under boards and branches were not venomoid. They were of course planted to be "found" though. It's always amusing for an experienced herper to see somebody on TV pulling out a "wild caught" snake from under a rock that is completely flawless, freshly shed and obviously has not missed a meal in its entire life from its perfectly square body conformation.
There comes a point with kings where you have to grab and pump them. We use Diazepam as I mentioned to reduce the stress of assist feeding on the animals, and Mazuri or Walkabout Farms carnivorous reptile gel slurry delivered via a feeding tube. If this animal is looking seriously emaciated, you may want to resort to assist feeding.
http://www.snakegetters.com/demo/vet/