So this is the conclusion I came to, but I want to ensure the threads are co axial, and the internal diameter of the shell is currently the major diameter of the threads, meaning I would have to braze in just threads, which might be impossible. So my current plan is to bore the shell on both sides in the mill, and then either braze or loctite in steel shells, bore then and then cut threads.
I had considered this, but honestly the crazy mill setup is easier. After measuring the frame, the BB is well centered and in good alignment, so moving it seems a bit crazy. I think for the minute, I'm going to crimp the chainstays and go from there.
So this is the conclusion I came to, but I want to ensure the threads are co axial, and the internal diameter of the shell is currently the major diameter of the threads, meaning I would have to braze in just threads, which might be impossible. So my current plan is to bore the shell on both sides in the mill, and then either braze or loctite in steel shells, bore then and then cut threads.