1. The green at the motor is needed for running and parking, the earth at the motor for parking only.
2. One source indicates that this system is also used for their MkI GT single-speed round-bodied motor
Showing the connections. It looks like the spade connector on the green wire should have a 'fin' so it only fits one of the two shrouded spades, but replacement harnesses may not. If you get the two coloured wires the wong way round on those spades the fuse will blow. Get the black and the black/green the wrong way round and the motor will run all the time the ignition is on: (Moss Europe)