I used a scribe pick and a jewelers file to reform the threads and remove the major defects.
Rear element reassembled. Putting the rear retaining ring back was a bit of a joy...After that kind of damage, it will never go back on like new. I lubed it up a bit with some grease and used the scribe to carefully put it back in. It took a little bit of cohesion and some light tapping with a rawhide mallet to prevent cross threading but it went back together eventually. I put some black electrical tape over the entire thing to keep dust out because there was some minor air gaps between the retention ring and the barrel due to the deformation.
Most thorium glass lenses from this era will have a slight yellowing. To reverse it, stick the lens under a UV lamp for a week or so and it will be good as new. The yellowing will affect overall light transmission and reduced contrast. With color films--It was crate a color cast. Here you can see I also polished the brass aperture ring. Its my lens--Im an eccentric shooter--Ill make it my own. If I ever want to spend the $700 for a perfect lens, I will keep it all stock and pristine.
