Can a motor from an M3 replace the 3.0 motor in 330ci, any complications if so?

Hello, You are better off buying an M3. Of course the engine can be bolted in, but the chassis may need modifications to do so. If I were going to attempt this, (I would not), I would buy a complete but wrecked M3, and put all components from the M3 onto the 330Ci. There are so many components on the M3 that just do not exist on the 330. Your better bet is to modify the engine in the 330ci or just buy an M3 used. I won't even get into the electrical portion.