Yes, the front struts bolt on (gear EARLY 500E struts, a little stiffer), and all four springs work as well. However, unless your W124 has self-levelling suspension, I would not go with 500E springs in the rear, perhaps SportLine rear springs and shocks in the rear.

You could do SportLine front & rear, which would be more sportier/stiffer than 500E, but still not slammed.

:-) neil