You need to have a lot more angle on the rear shackles so they don't rotate past center at max lift on the rear of the car
I would relocate the upper bushing hole forward two to three inches closer to the rear end to increase the shackle angle more, you can test where to put it by removing it and move the top part forward until you see what angle you like, it should be rotated forward while testing to see where you want it
I'm thinking more like a 45 to 60 degree angle instead of 25 to 40 degrees