Boy, I almost forgot I started this posting.
My steering at highway speeds has been improved greatly, not by doing something to the front end, but to the rear.
At the time I started this topic in Jan, the car still had it's original coil springs and some old Monroe shocks at the rear.
Also the rear sway bar was rendered useless by the fact that some previous owner had it cut. Don't ask me why, but it was cut by a torch.
Since January I have replaced the rear sway bar, sway bar links, coil springs, and replaced all 4 shocks with Bilstein.
The car drives much better at highway speeds now.
I do still have some work to do for the front end.
I am sure the steering could be a bit tighter if some things were replaced, like the steering damper, though my first priority is the lower ball-joints.
The driver's side ball-joint boot is split, bone dry and making grinding sounds.
Hell you can feel it in the floorboards, unfortunately it doesn't look like a DIY.
The ball-joints have to be pressed in and you need a special tool to get them out, to do all this the wheel spindle has to come out.
Tomorrow I am going to see what my mechanic will charge to do it.
The weather is only starting to improve here in NJ, though, on the days when it's warm, it's usually raining.
I want to get a look at the steering column itself under the dash, to see if there's any tightening I can do there.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member