What rectifier is it Ratch? I fitted a GPZ750 one and it had three yellow wires that connect to the three wires coming from the alternator on the rh side of the engine, the other two were earth and power out.
Looking at a Z1000 wiring diagram from the same era, Black with yellow trace is earth, brown is a 'switched' live & white is the main feed from the battery +ve.
Any manufacturer markings on the reg/rec you have?