Does the stock shifter knob use a permanently threaded insert or do you make your own threads as you tighten down the knob? What happens if the knob ends up with the pattern upside down, or was it designed to prevent this? How do I make sure it is torqued properly?
crank it down tight - it should be very close to being straight - I would be suprised if it is not. But, if not back it off till it is straight. You should have to back more than a 1/4 turn; the knob will still be plenty tight.
You might be able to fit a stop nut on before the stock shift knob, you can adjust it so that the knob stops where you want it. I know that it works with the cue ball style like Roush and Hurst, might be worth a try with the stock one.
Is the threading on the shifter a tapered thread, which would explain how it gets really tight as you crank down the knob? I am contemplating switching to the IUP shifter knob but I don't want to mess up my original knob if I can't ever get them torqued and timed properly.