I did the conversion and like it. At first I though I noticed a little more sway around town with no load but on the highway at high speeds 80 plus with a heavy load it is great. I had also put on new tires so it may have been the extra rubber that was soft. I may try the thicker Volvo sway bar and see what that does. You need 2 softer spings, 2 nivo shocks FCP has lifetime warranty and great price, 2 volvo spacers for on top of springs. The spacers may be optional but I put them in. Each one is about 1/4 thick.

It is really nice to put any weight in and have the height right and a great ride with no bottoming out. Go for it...

Hi Spook, The nivos will work great, same ride if not better. If you are hauling large loads like I do(more than 400 pounds) I kept the springs and used the Nivos, but the ride is a bit harsh with no load, plus it looks like a 60's car jacked in the back. All it takes is four bolts and Bam! your done. 1 hour the most. Pauli

Yes, they can, with, as you say, special springs.
No modifications are needed.
My wife's '90 765 has Nivos (fairly new); the ride isn't much different than the Boge turbo gas I also had on it (with ordinary wagon springs).
The stock blown ones, OTOH, were truly abominable.