I have a 2004 bmw 320cd coupe and was looking to put a petrol 3L engine in it? would it be worth it as the body is in really good condition, no rust underneath or just get rid and buy a 330ci? What parts could I keep and what parts would need swapping? gearbox, engine, ecu, ews?, dash I know petrol to petrol would have been a ton easier, hwat about legal issues such as informing dvla, road tax and insurance? anybody seen anything like this done?