I don't see why you are having this conversation.... A pic16f877a or equivalent.. with a FD controller chip and a 23k256 SPI sram.... Job would be relatively easy..
If it was 'easy' why was it never done?
Although adding two extra chips to make it possible isn't really 'easy', certainly not compared with interfacing an SD card.
As I've said, it was discussed endlessly on the PICList, by people FAR above my capabilities.