When I installed my Ford small block into my 190 I weighed each corner and found I was about 20lbs. lighter than a 2.6. Considering the weight of a 2.6 vs. a 3.0 with the same block, I'd just get a set of Eibach springs for a 2.6. With a set like this you'll find that the rear spring rates are changed very little as the most weight differences are in the front. I'd also recommend that you change the front sway bar to a minimum of a 300TE to a 400E to a 500E in steps. My 190/5.6 ended up being 53%/47%
with a total weight of 2988lbs. with the battery in the trunk over the right rear wheeel naturally!

Tobias MB
4 MBs