Hotchkis rear sway bar install

You need to set the brackets flat against the frame rail before you weld them. Your car appears to be missing a bunch of stuff (shocks, exhaust, drive shaft, fuel tank, etc...), which means it's light and is sitting higher than it will when it's fully assembled and at final ride height. With the springs compressed more you won't need longer end links. Pretty sure the instructions say you need to have the car at final ride height to do this properly, which means fully assembled too.

Regardless, put the brackets flat against the frame rails. Longer or shorter end links are part of fitting the bar to your car and its ride height. Don't modify the frame rails to use the out of the box end links, which might not end up being the perfect length for your particular suspension set up and ride height.