Per your PM - the '81 probably doesn't have the shift kit. My notes say it happened in mid-1981, applying to most of the '82 models. Might depend when in '81 your tranny was built. Easy enough to tell; when the shifter mechanism comes out just compare it to the pics on this page
It should have the non-X 5th gear, as the X gears started halfway through the '82 model year. Of course it could be possible you have a later tranny in the bike, so look for the X on all of the helicals before you act. I don't think there's any real reason to presume your existing 5th gear is bad, unless you ran for a while with water in the oil or with a totally trashed bearing somewhere; your decision on the tall 5th will probably come down to whether or not you want it.
I'm glad you found a local shop that is competent with these. Seems pretty rare these days. Dealership? That'd be even rarer.