Welp, I got my new modified spacer and bearing in last week (thx Armen!) and got them installed over the weekend (thx for the write up Dragbikemike!).
Took me about 3-4 hours total. Mainly, the heat/cool part and then adjusting the belt in the pulley since I don't have much wiggle room with the larger front pulley mod.
I never did any proper measurements of the pulley deflection other than grabbing front to back on the pulley and feeling a fair amount of play but it's been that way for quite some time (25k mileage). I always figured it was play in the rubber dampers that was causing it.
I have the modified front pulley too for those of you who are interested. I was a bit concerned that might be a problem but it wasn't really.
I've only had a chance to take it out on a couple of short runs after the install but holy heck, what a difference!
Absolutely no wobble now. One thing I didn't expect was that for the longest time, whenever I would lay the bike over in some steep turns it always felt a little sloppy coming out of the turns.
I figured it was just my imagination but with the positive contact on the pulley now I realize it was probably just pulley wobble...it is actually quite a different more confident feel.
If you're considering this mod I highly recommend it if the back end of your bike feels a little squirrelly.