Bumpsteer is more of an aggravation than a danger; you will learn to compensate for it somewhat as you drive the car more. Little bumps in the road will have little effect; big dips or waves in the road will be more noticeable. The setup you have will tend to pull right under acceleration and left when braking. You will learn to correct for it with steering input. As Dave said, the amount of bumpsteer is directly proportional to the deflection of the front suspension. I am more concerned about that welded Pittman arm; just make sure it's gusseted properly and you'll be good to go.