I'm pretty sure Superformance and the Backdrafts use the same filler / locking caps assemblies. Both cars made in SA.
(both caps appear the same and the keys have the same cap manufacturer logo "PJ")
The non-locking for the SPF is NAPA 703-1687. I'd give it a try.
https://www.napaonline.com/en/p/BK_7031043
One thing of caution: This may be a non-vented cap. You may have to mod it with your trusty drill.
Edit:
The Moto-Rad (manufacturer) site shows fitment on a 1978 Corolla. Which is vented.