AFAIK, they are not a direct swap... pretty sure they are narrower, and the bases will definitely not bolt in.
Other 124 seats are plug & play, with the exception that the V8 bases/frames are narrower, but you can swap the cushions around. So if you found some nice 300E/E320 seats, you could put those cushions (bottom+backrest) on the V8 base/frame. But not the 190 stuff.