We drilled a 1 inch hole in the rear shackle area of the frame inside of the OEM rear mounts and press fit some thin wall DOM tubing to the press fit outer and the shackle bolt's rubber bushing size. We still had the rubber shackle bushings in the spring eye.
We used some old school 'Cal-Custom' long lift 'Chrome' shackles but re-drilled the 3 hole side to a 4th hole at OEM size and cut off the extra 3 holes then used the bolts from the kit....
I think we added 2 flat stainless washers to the outside spring eyes and 2 to the top frame bolts to help with the slight miss-match top to bottom.
I don't have pictures of this and the car is 30 miles away. And I am sipping some 'Makers Mark' getting ready for tomorrow. (Thanksgiving Day 2019).
Stinking outside the box