The lower ball joint installation is best accomplished with a Mercedes-specific press. If the installation was done by some other means, it is possible that the ball joint was damaged. This can occur if the joint is pressed in by applying pressure to the top of the joint instead of at the flange. I would be tempted to disconnect the steering arm from the steering knuckle and see how much effort was required to turn each wheel by hand (wheels off the ground). It is reasonable that the alignment is off, as past alignments compensated for worn components and no-doubt sagging upper control arm bushings. Your camber is probably quite negative. I recently did the front end on my "82 300D. The steering was a little bit firmer, but certainly not "hard."