Yikes!, I didn't think that a BB shell can be that soft!
I wonder if you can insert a pipe through the BB shell and slowly and carefully pound downwards at each end, very close to the BB shell faces on both sides of the shell, moving the pipe around as needed, and hopefully get it as close as possible to perfect roundness, then chase the threads on the shell and re-face it too. At this point, you might have nothing to lose with the frame and even the most aggressive solutions might be worth considering.