Finally get to pretend I am one of the cool kids - Holley kit swap
I ended up just cutting the perches on my rear end and aligning it to my trans to make it all work when I did my T56 swap. Though I got to do that job twice due to a oopsie. When I first built my trans crossmember, I had left the transmission on a floor jack overnight and didn't realize it had sagged when I went to make the templates the next day. It sat so low that it ran my fuel rails into the firewall and eventually caused a fitting to leak (plus it hit about every rock in the road along the way). Regardless, at this point I had cut the perches on the rear axle and rotated it to match the powertrain angle. Once I figured out my mount was all sorts of off, I jacked it all back up, remade the crossmember, and cut the perches once again to roll the axle to match. Never cared what the actual angle was because I was just trying to get it tight to the floor to give me good clearance.