Robert,
I'm going through changing the whole suspension on my '84 190E for track use only. I've used old MB struts, cut, new threaded sleeves welded on with dble. adj. Koni competition inserts. I'm using the road race inserts with shorter travel but they make one longer. My 190 has a stroked 302 Ford in it. May not hurt to do like the off-road guys do and add an extra shock!

Spring dimensions:
Front: OD 4.308", ID 3.163" free length 13.5"
Rear: OD 3.868", ID 2.808", free length 11"

These are the dimensions for the 190/2.6 Eibachs I just removed
and the rates according to Eibach were 319lbs front, 359 rear.

I've now got 541 front and 644 rear by using MB springs. To get that rate the coils are cut. For your use I would suggest using
Hypercoils, 2.5"ID and going with a high rate and length for your 'landings'. The springs are not expensive...$50-60 each and have rates up to 1300 lbs. Might not hurt to use a shorter high rate and low rate springs together to make a variable rate. I have the formula for finding spring rates also.

If you'd like prices for custom shocks I work with the Carrera Custom rep. for unusual fitments and applications as he is my neighbor. He has many contacts with most performance shock manufacturers.

Send me an email to discuss this further.

Good rallying...
Tobias MB
190/5.6