If you have attic space it is easy to relocate the old Jb in the rafter and put a new one with the higher temp wire in the place of the ceiling outlet.
If you have attic space then there should be no reason why the knob and tube can't be replaced.
Knob and tube wiring is 60+ years old, has no ground, and SHOULD be replaced, regardless of the condition. Everything has a lifespan, including wiring.
Just because the Code allows us to protect a K&T circuit with a ground fault protector or install a loomex jumper (or high temp sleeving) to make fixture boxes 90C compliant, in my opinion it should only be used as a temporary measure until replacement is done. I'll get down off my soapbox now