Ah! That makes sense. Cool idea!
Not to be pedantic, but its not a 2-card system as most would use the term. Typically a 2-card system means that a pair of cards can be encoded into a single ELEMENT. A traditional PAO is a way of encoding 3 cards into one SCENE, but it’s not a "3-card system. It uses 3 elements to build that scene, one per card, so its a single card system.
Your system is structured a little differently because it uses one element to represent two suits, but then needs two more elements to represent the two values. So yours is kinda of a “0.6 card system” because you need three elements to encode 2 cards. It offers a less than 1-1 compression ratio per element.
At the end of the day you’ll need to accurately encode and then recall 78 elements to memorize a standard deck of 52 cards. This is going to be trickier to pull off than a regular PAO, at least at speed, but it might work well for how you visually process the card indexes.
Let us know how it goes!
More on the phrasing of “X-card” systems and the idea of elements, images, scenes, and systems here: