MG? does the connector look like this on the motor?
the connect to switch at "2" i believe is the park connection, feed from ignition would be keyed hot, the MG motor would have a rack sticking out of it on one end. i think all MG's were lucas the switch is a specific toggle for wipers, or you can buy a switch(rotary) from cole-hersee, but it will have the international pic of wipers on the knob, of course you can switch the knob to a more vintage one..
whether the chevette switch is correct for parking that motor ? who knows? i would bet no...