It's only part of my issues. One is the perch hole not being large enough, the other is the perch to strut mount fit is not nice. I'm going to replace the perch with this one piece spacer/spring perch:
The top of it will seat in the recess of the strut mount (see the 3rd picture I posted), bottom of it is the spring perch, and there's a 23mm hole for the strut shaft. We'll have to see how that thin area at the top will do after some driving.
p.s. I've measured 2 sets of rear spring perches from GC, both are 20mm holes.