I guess, this would be the starting point for parts:
http://www.etk.cc
This would be the catalog for e.g. the USA F56 S with the B46 engine:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B46/USA/
From there through "84" to the adapter:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B46/USA/84/84_0960/
http://www.etk.cc
This would be the catalog for e.g. the USA F56 S with the B46 engine:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B46/USA/
From there through "84" to the adapter:
http://www.etk.cc/bmw/EN/search/selectCar/F56/HC/BMW+Cooper+S+B46/USA/84/84_0960/