I think that if we are only talking about mentally photographing the printed page, then the fact that that page contains a bunch of numbers should make no difference.
However one question is, what the subconscious mind will make of a completely irrational number like Pi, that does not repeat itself, has no pattern, and therefore cannot be cognitively "processed" in any way, apart from storage in long-term memory.
Photoreading requires activation, and I'm not sure how Pi to 22000 decimals is supposed to "gel" in the mind if the mind cannot do anything with it, i.e. look for patterns, etc.
Therefore my 2 cents is that this will probably work best if it is approached as a traditional memory exercise, like remembering decks of cards or the telephone book.
Even if it also works with photoreading, for me the most important part of photoreading is to understand something, and with something like Pi, there's not much to understand.