It can be done, but it makes a worse product. EVs are built to fit batteries and motors in the most optimal place. Likewise with ICE cars with engines and transmissions. What you end up doing is shoving batteries in the engine compartment which is shaped wrong and you significantly change the balance of the car. You leave much of the expensive parts of the ICE car, while adding more expensive parts. It just doesn't work well in practice. If you are going to spend time engineering, it is better to engineer a proper EV than try to shoehorn an EV into a size 6.