a couple of additional things.
Test fit the bushings over the shift rods while they are out of the car. Before removing the rods, mark with a permanent marker the fore and aft points of contact of the bushing and the rod.
Now, if the new bushings seem loose on the test fit, build up some material on the shafts at these points. I have used brazing rod and lead plumbing solder. I now think that JB weld would be the easiest thing to use. You want to build up the rod, then sand it down to give you the best fit in the bushings.
Rebuilding the bushings in the linkage is only 1/2 of the job. The other half is changing the bushings and the centering spring in the shifter itself. Cost of the parts was $45 from a Porsche dealer. Parts are listed on the last page of my tranny rebuild article.
http://home.san.rr.com/pb914/rebuild/Lastly, the best thing you can do for shifting is to convert the Factory 6 tranny to sideshift the next time you have the tranny rebuilt. This did more to fix my shifting issues than anything else!