Leaf spring bind?

Was helping a buddy out with his car today. (66 Belvedere wagon)
He recently rebuilt the suspension and the driver’s said leaf spring is super arched and the shackle is all the way forward and resting on the floor.
I told him I would take it all apart and inspect everything but I’m not sure what would make only one leaf arch like that?
Any advice is welcome and appreciated

The rear end has extended too far and allowed the shackles to flip direction. Either poor work habits or too long of shocks. They can be flipped back. Shackles should be slanted toward the rear.

I understand that. The passenger side looks perfect. I have not touched any of the suspension yet. Not sure? My first question was if he torqued everything down with the car in the air

Get the weight "almost" off that driver's side and get under there with a large pry bar and pry the rear of the driver's side leaf spring down, which will cause the shackle to come down and back. This might result in a startling loud "POP" as the leaf spring pops into position, so be forewarned. The correct shackle position is for the upper shackle eye attached at the frame to be "a little" forward of the bottom shackle eye at the spring. Straight up vertical eye to eye is acceptable, while top eye behind the bottom eye is incorrect.

Thanks Rusty. Will do this Sunday. I’m going to help install motor and transmission. Prepare for the next steps.