Funny, I've been fighting a wander on my 86 with the stock arms. It's like you are being blown around by the wind. Very subtle, but there. It's been aligned three times. We've tried some varying settings and it gets better, but never goes away. Everything in the suspension, steering and tires have been replaced. You name it, it's new. I will guarentee you that whatever you name has been replaced. Only the space-frame is the same.
Still wanders. Not bushings, not cradle mounts, not rack, not bearings, not tie-rods (inner or outer), not tires, not steering column, not shocks, not bearing caps, not brakes, not front suspension mounts, not motor mounts, not alignment, not, not, not....
It sounds like you've added the bump-steer kit and your's is doing the same thing. Mine is not roll-over steer or bump steer.