Lord Chocolate

I have recently started working on a mod in 1.7.10 (for compatibility with the Lord of the Rings Mod, though I would be fine with an answer compatible with 1.12.2) in which I plan to add a new dimension with extremely different terrain generation. I would like to implement 3-dimensional chunk loading (to allow a higher build limit), and a new way to save chunks that might require less hard drive space; however, the chunk generation classes (and all the classes that use them) use methods that access/find a chunk with only its x and z coordinates, so adding a third dimension to chunk loading seems to be impossible without massive code rewrites. If all those rewrites are required (as I expect), my question is: how/where should I link the new generation code into the game so that the original chunk generation/saving code doesn't interfere? I know 3D chunk loading has been done before: https://github.com/OpenCubicChunks/CubicChunks However, their method seems to use normal chunk generation and add onto it, as opposed to completely replacing it. Thanks in advance for any help! I have moderate experience with Java but am not that familiar with the tools Forge provides.