Because you used springs to lower the car,the relationship between the steering arm and the lower control arm hasn't changed from stock. The steering arm on the spindle is 5/8" lower than it should be. This causes the toe angle to move inward when the front rises and outward when it falls. It causes the car to turn one way under acceleration and the opposite direction under braking. This is bump steer and can only be fixed by using a taller lower ball joint or buying an aftermarket spindle with a relocated steering arm. I know of only one aftermarket spindle that does this.
Can you still benefit from a taller upper joint? Perhaps.
Look to see if your upper control arm is lower where it pivots at the frame or where it mounts to the ball joint. The center of the pivot point needs to be lower than the center of the ball of the ball joint.