Physics rule. So tonight I pressed in the steel sleeve into the aluminum bushing. Worked very well with the measured tolerances we figured out... I did make it a little easier by placing the sleeve in the freeze and the bushing in the oven. (by the way, 350 degrees seems like the optimum temperature, haha.) I didn't go too crazy as I had to replace a brake booster (WRX in the background...)
After the bushings were together, I put them back in the freezer to cool, then pressed them into the differential support. I had to center the bushing a bit as they aren't stepped like the stock rubber ones, but that wasn't bad.
Once everything was pressed in, I placed it in the rear cross member and it fit perfectly. I mean no prying, no bending, just slid in perfectly. There is a little slop in the stock hardware and stock cross member, but as for the support the bolt holes are exactly the correct width. Once it's torqued down I'm sure that will be removed.