I can only explain it with my homebuilt EI. Six wires come out of the alu box, which need to be connected. Black, Green, Blue male, Blue female, Yellow male, Yellow female. As Bryanj explained you can split the original Blue and Yellow wires close to the rear brake switch, not far to the right from the bottom of the battery. I looked it up and your model is no exception. If you can't find them, just follow the wire (combined and extra shielded) coming out from under the points cover and follow it, first a bit to the rear and then upwards. Somewhere there the blue and yellow connects to the blue and yellow in the harnass. You can disconnect these connectors. I've connected the female Blue and Yellow from my unit to the males of the original wires coming from under the ignition cover and I've connected the blue and yellow males from my unit to the original females in the harnass dangling down after I disconnected them. It's very simple: I just interupted the original wires and put my unit in between. The location I chose for my unit, is ideal, as it sits right where you can interrupt the original layout. Now my unit needs ground and power ofcourse, so these wires (Black and Green) are an extra compared to the original layout. Now the Ground is easy. The Batt NEG terminal is right there. Now there's just one wire left to connect and that is the black one of my unit to the POS. The Batt POS terminal nearby is a no no ofcourse, because you don't want the unit to be ON all of the time. We need switched power. Now you would think any black wire is OK, as black means switched power with fuse and all. However possible, for me this is not ideal, as I like to be able to do maintenance with the key switch ON, but the ignition switched OFF (by the killswitch). So the power my unit needs, is ideally under the same regime of that killswitch, just like the coils are. So I have connected the black, the needed POS for my unit to the POS wiring to the coils, coming from the killswitch.
After writing all this, have you considered leaving the ignition original? The system is more than adequate to ignite at all rpms. Not that long ago, just out of curiosity, I did a measurement of the peak voltage in the primary of the original breakerpoints ignition and was surprised to see it well over 200 Volts. That's a healthy ignition.
In other words, just don't expect too much of an EI. The standard Kettering ignition is simple and more than adequate.
Edit: the pic may lead to confusion. The Ground wire to the battery NEG terminal, is not Green, but Green/Yellow. I had that wire lying around and in housing in Holland Green/Yellow is always ground.
