Lets talk Autocross

I would think a rear sway bay will compensate for the relocated springs some. The ride height of the car is very important especially in the rear. If the back of the car sits high it won't go round corners fast.
I have the car low enough that will not be a problem. I was thinking the same about a rear sway bar and the relocated leaf springs
Did you happen to install offset bushings?
I did install the offset bushings and the stiffener plates on the lower control arms.
If having the ability to tune for an Autox is what you want, throw on a Hellwig E-body tubular rear bar. Its 3 way adjustable, about $175 and clears a spring relocate if you mount the dogbones on the inside of the bar eyes. The upper mount needs some reinforcement still in the pic, this was just the first mock up.
Good to know that rear bar will fit with the relocated springs. Did I read somewhere you weren't running the rear bar because it made your car tail happy.