I'm sure the swap is possible, however I don't imagine it would be easy.
You're probably looking at major surgery to the front of the E, not to mention countless little details once the motor was in there, i.e. rerouting and relocating wiring, vacuum lines, fuel line etc.
I've seen a BMW 318ti with a V12 shoehorned in the engine bay. This was done by a tuner in Italy, and as I recall the whole front end was basically replaced.
If you were to pull it off, it would be one hell of a car.