If you have a tap and die set, that is a pretty easy job, get a plug fitting for the knob, drill it the size needed for the shifter threads and cut the new threads in the plug. If the plug does not have enough meat for the new threads, you might drill out the shifter hole to use a bigger plug.
This shifter knob was an old stone door knob I just sanded and polished and used a plug to get the right threads.