The steering box is one of the few achilles heels of the 123 cars.
I just thought that you should know that a month or two ago, one of the professional MB techs who frequently chime in warned that MB reccomends not adjusting the steering box, he said that it can cause problems. I take his advice seriously, but it was after I've made many adjustments to boxes in my own cars.
If you do get it too tight, you will know it in two blocks. Keep an eye on it.
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in