An internal FIFO that stores 256x23000? Are you targeting a device with enough memory?
All I'm saying is that if you're data is chunked up into 256 bit segments, but the first word has unused lower bits(i.e. bits 0-143 might not have data), and some unused(don't care) bits on the last word, then you're still utilizing the memory bits very well, as everything in between will use all 256 bits of each word.
I don't think that's what you're asking though. Are you asking, when the first bit of data comes out, do you want to align it to the 0 bit? I guess I'm not following the problem.