More likely the engine has been replaced with one from a newer bike.
Two different ignition systems were used in this family of bikes, the Capacitor Discharge Ignition (CDI) as used on all CX500 models except CX500E and 1982 only CX500C and the Transistor Amplifier Ignition (TI or TAI) as used on the GL500, '82 CX500C, CX500E and all CX/GL650 models. The TI system is powered by the bike's charging system, which has a pretty standard 3 phase (charging only) alternator. The CDI is powered & triggered by extra windings on the alternator's stator.
(Note that, while both stators have the same footprint, the TI stator is rated for 252W but because so much room on the CDI stator is taken up by the special windings there is only enough room left for a charging section rated at 150W)
I believe that an Ignitech ignition made for a CDI engine can't be adapted to work on a TI engine because it needs some of the CDI stator's special windings.
Note to Blocker1, Thunder Muscle and any other new members who see this:
Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).
NOTE that the paperwork in the UK and some other parts of the world shows the year first registered, not the model year (US and Canadian papers show model year but I have been unable to find out which Australian paperwork shows). This is important because there were changes from year to year and the wrong year's information may not be applicable to your bike.
And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).