Marti,
I have recently had a rebuild on my suspension which included Bilstein shocks all around. The Bilsteins raised the car up by 2-3 inches in the front and by 1-2 inches in the back. I then changed to John Olson springs which helped lower the car more to the stock clearances but still a bit too high for my taste. I had the shocks checked for correct W113 part number twice and all was fine. If my shocks pads are indeed the smallest pad available, I am leaning towards getting the Koni's because I hope they will lower the car to get a more aggressive stance and get better handling (vice cutting the springs which I still may have to do).
If you (or anybody else) are so inclined to getting Bilsteis I could make you a deal on my relativley unused used shocks while I get the Koni's. If you want a more stock, luxurious, and comfortable ride, then go for the Bilsteins; but at the risk of raising the car's height. However, if you want a more sportier feel but at the risk of feeling the bumps more, then get the Koni's. In addition, the Koni's do have a adjustment to change the firmness.
In addition to the other items to check as mentioned by the other readers/writers, have the kingpins checked.
It is also nice to have options, but have as much information at hand before you do choose which path.
Cheers,
Danny
1970 280SL Euro silver manual