Thank you both for your help.
It had bugged me that on paper the 74hc595 wasn't really up to the task, yet so many people online seem to use them for just this purpose?
I agree I would be better off flipping to 32 cathode columns and then scanning the rows using 8 high side switches, so 4 daisy chained TPIC6B595 would be best for that.
For the switching of the 8 rows, I am unfamiliar with mosfets and would ideally like to stick to BJTs if possible. Would something like the BC639 be unsuitable then due to the current gain?
Thanks again