Yes, 1980 should be BTZ.
CDI systems have in-built coils/black box and you can't change one without the other.
The BTZ system has separate (dual/single) coils and 2 black boxes.
To be honest, it's not so much the coils but the aging wiring on the pick ups, the crude advance/retard in the ignition curve and the puny single phase alternator chucking out something like 125 Watts that need replacing first.
Bite the bullet and get a proper Redax conversion. You get Nology coils, 3-phase alternator and modern reg/rec, new pick ups and wiring, and a programmable (if you so wish) Ignitech black box.
Replacing the coils alone will give you little return for the bucks unless there is actually something known to be wrong with them.