Why not reupholster your E30 rears or try an E30 M3 setup. Anything an be made to fit anywhere but is it worth the time and money? I believe the seat back width to be different and the 4 dr and coupe are different again. Have someone get you the measurents and the type mounting to see if it is even worthwhile to try. Better yet locate a possible donor car, ie. at a salvage yard or measure it at a dealer lot, and for yourself. It only cost me $500 to redo my entire interior in fabric (leather too hot for me in the desert). I had estimates as high as $1200 for the same thing. Good luck.