Thanks for the information, For my project, I will do a 888 LEDs cube with 8 layer of 8 by 8 LEDs (anode in \, cathode in \), then I'll mutiplex two layer of transistors 8*8, one npn and one pnp, so like that I would be able to light each LED one by one by powering one npn and one pnp. So two 74hc595 for the npn, same thing for pnp. Does shift out gonna be enough fast so we can see all LEDs light at the same time? I know it seem complex, I can post a draft schematic.