Does anyone know an enterprise which makes electric core-kits for old Mini Coopers to convert them to EV vehicles? A garage should be able to remove the patrol-engine-core from the metal shell of the car and fit this electric core-kit into the shell, and after that car should run like an EV vehicle. The kit should come with the rear axle fixed with the electric motor and inverter like in Tesla cars, and batteries could go under the front hood, the seats and where the petrol tank is to give at least 220 km range. And this kit also should have everything else that is needed for an EV vehicle including new wiring.
There is nothing quite so highly developed. There are some companies who do offer kits with motors, inverter/controller, battery modules, etc, but the volume is too low to support the development of the highly-integrated system you suggest. One of the better-known companies offering this kind of system is EV West. Here is a link to their conversion kit page.