Look at my posts in this thread but ignore the original poster because we won't listen to someone who has done this kind of thing before and intends to do non class legal mods.

http://www.peachparts.com/shopforum/performance-paddock/342744-w123-racing-setup-serious-questions-within.html

You can get around the 4 matic special front spring issue. Have a look at a later Honda and I think later MB 4 matic. These use a forked lower mount to get over the drive axle and a strut / spring combo. You could even get a "coil over eliminator " from an oval track race car supply house that should work for your app.