Hi!
Here’s a description of how I mapped cards to numbers for easy reading via the Major system. Not sure if you use that for numbers but I use the same suit to number encoding:
In terms of binary, what you’ve suggested is a great idea. 3 binary digits per chunk, translated to the actual number. 000=0… 111=7. Do this twice and you’ll get a 6 digit binary sequence converted to a 2-digit number between 00-77 (excluding the x8 and x9 numbers.) If you have a 2-digit PAO list, you can store 18 binary digits in one PAO scene.
By the way, the title of your post says “3digit PAO”… Are you looking to expand to a 3 digit system? That opens up lots of new possibilities for data compression per element with 3 decimal digits, 2 cards, and 9 or 10 binary digits per image!