Do you have the engine, software, etc... already? If not, you might as well sell your 328ic and buy a E36/7 (Z3 M roadster/coupe) or a e46 M3 with that engine already installed by BMW. The cost of the conversion (ie parts, labor) will be so much. If you plan on doing the conversion anyway, aside from the engine, software, etc... you will need to upgrade the suspension, brakes and the coolant system. You might be able to get away with the same gearbox. I am sure other members know more about this than me, but this is just my humble opinion. Let me know how it turns out.
