Hopefully your welder will know better but do not weld it in place and remove all non-metal parts. Otherwise if you are lucky things will only melt rather than catching on fire.

You'll get hit with whatever is their minimum charge - US$50 - $100 depending on your area. Though if you catch him/her at the end of the day on Friday a cold couple of six-packs can sometimes suffice....

If they suggest brazing rather than welding I personally would do it. There isn't _that_ much force put on the shifter.