Would it be hard-coded into the game itself, or to the save file of the world that was made? I understand that through CubicChunks that where it differs from regular Minecraft is that instead of it loading in a 16x256x16x chunk space, it rather loads chunks by 16x16x16x making it as you said, go beyond the limits. I am simply trying to edit the world save file so in it would allow 16x(256x+64x negative)16x (If that is to much, remove the top build height from 64 and allow that 64 to be within the void, making the top build height x192 from 0 with the addition of building into the negative by x64.) All I can say why this has to be is because of a story that I am trying to help build.
