For starters the E34 is 2 inches wider that the E30. Also, I don't know if you can see it, the E34 shock mount is on the top of the control arm. The E30 shock mount is on the bottom of the arm.
Finally, E34's use coil over shocks where as E30's use springs separate from the shock, so there is no spring perch on the arm. I suppose you could us a coil over set-up on your E30, but for the sake of argument, the perch is missing from the E34 arm.