Shift Knob Rusted On Shifter

[Ford1931]

I have a very nice early mushroom style shift knob that is rusted to the shift tower. I have turned it upside down in a vise and have been soaking it often with the acetone, transmission fluid 50 50 mix. I even tried heating the shift tower. I have tried turning it with a band clamp wrench. I am trying to be careful as I do not want to break the knob. Anyone found anything else to work? As a last resort, I could probably cut the tower drill and re tap it.