Well on further research, KYB brand lists the same part number for front shocks for both W123 and W126. Promising! Also, Monroe has different shocks for the two cars, with the following compressed/expanded specs.

W123: 15.125" / 20.000" (stroke: 4.875")

W126: 13.625" / 18.375" (stroke: 4.750")

More good news! If Monroe's products are any indication of what to expect from Bilstein, W126 front shocks have a 50% travel height 1 9/16" lower than W123 shocks. So now I have a target ride height!

That question answered, I'd still like to know of any first hand experience running W126 shocks and their damping characteristics on the smaller car.

__________________
1984 300TD Turbodiesel - 272k
- Daily Duty
1985 300D Turbodiesel - 315k
- "Recommended for competition events only"