Spring Relocation Dimensions

I bought a spring relocate kit from a member; It didn't come with the tubes for the rear shackles. (Car is '71 Swinger.) Here's what worked for me...
I took one rear spring bracket and centered a 3/16” fender washer over the hole on each side, brazed them in place then opened up the holes so that a ¼” drill bit fit snugly down the center of the bracket. I bolted the bracket in place and with an angle drill and an extra long ¼” bit, ran the bit through the bracket holes and drilled through the frame. Actually, it took two bits… One cut to length for the near side and another cut to length for the far side of the frame. This placed the tube on the same center line as the old mounting point- just inboard.
A friend made me some tubes with the ID accepting the rubber bushings and the OD at a common size that matched an available hole saw. I went back with the hole saw and used the ¼” pilot holes in the frame to make the final opening. Welded ‘em in and reinforced with plate. Came out nice.
It just so happens I had my friend make an extra set of tubes just in case I screwed up the first ones. If you’re not in a hurry, let me know and I’ll send them to you along with the modified bracket. I got laid off last week so will let you pick up the postage.
I suggest you install a front bracket and measure how far the front of the spring was moved ‘in’. Then, move the back the same amount.