Well, maybe you could tell me  how you would call it to produce an ip core with 288 IOs for a device that has only 167 (or so) soldered on a board with some SDRAM etc ending with  80 Usable user IOs? Btw, you could enligten me wich microcontroller you plan to use that can write 256 bits at once. There is no bottleneck in using  some sort of serialization at all. And even if there were, you could always reduce the bandwith requirement by implementing roll-n-times in hardware.