That is weird because the frame rails line all the way down the car and your wheel wells after the mini tub would measure different then? Like 15" on 1 side and 13.5 on the other.
I looked at your thread to your build and there are a few differences I noticed. Your lower mounting brackets for the links are about 2" shorter than mine closer to the housing. Your upper shock tower looks to be in a different spot and those tabs for the upper links on that bar are not pointed down, they are pointed back. So in a nut shell your pinion angle will probably not end up like mine did because everything is in a different location. I also noticed that your upper link bars are on probably twice the angle that mine are on. Make sure that your bushings are at the same angle on each link or they will bind when your suspension travels.......just a heads up is all.
Yes those 20's are HUGE!