I’ve only gone to 120 digits, so my system may not be as flexible as you’d like. But I discussed my approach here: My Approach to Pi (to 120 digits). I stored 6 numbers as three images per location in my memory journey.
If you take a similar approach—storing 6 numbers/3 images per location—you’re talking about storing over 16,000 groups of numbers. That’s an incredibly large number to me. If you’re somehow able to squeeze 9 numbers into each location, you’ll “only” need just over 11,000 loci.
Bob