Couple of other things.
Tried to do some investigating today on the potential clearance problem at that riveted joint on the u-joint. If theres a clearance issue I am missing it somehow. I unpinned the fork at the shift rod on the tranny and rotated it 180 degrees, repinned it, and with the shoulder bolt from the other half of the joint installed, I cycled it through its potential movements while selecting gears and while close I found ample clearance in all positions. So curious that, it appears if Subaru had reversed the drilling order and used an identical shoulder bolt at that fork it would have worked unless I am missing something.
On looking at the McMaster site, I also found a similar sized bushing(6294K88) that was available in Delrin and Teflon as well that looked like it would work. The only dimensional difference was 3/4" overall length vs 1/2" overall length that you used Josh. Any reason I might have missed you chose the shorter one? Any further upside to Delrin or Teflon?