Ok, to help get your head around it a little more - All an ignitor really is is a fast switching, high voltage, earthing relay.
When used on a carby engine (like a 4k) - its needed to earth the coil, when directed to by an electronic pulse from the elec dizzy, as the elec dizzy doesn't earth itself out like the points dizzy does.
When used on and EFI engine - When running ECU controlled ignition the elec dizzy/CAS gives the same sort of electronic pulse to the ECU as above. The ECU can then manipulate the timing and give out another delayed/advanced pulse for the ignitor to fire the coil. The ECU needs to earth the coil to fire it, and if it earthed through the ECU it would be giving the ECU the discharge voltage of the coil....... which will quickly fry your ECU. So all the ignitor does in the case is take the pulse from the ECU and ground the coil directly to an earth - exactly like powering something with a relay from a given trigger.
So what I'm getting at is you just need an ignitor. Doesn't matter what its really from as they all do the same thing. Working out what wires are what in/out of the ignitor would be the next problem though.