modify 1.21.8 to have caves until y0

Hi! I want to have the generation of 1.17 in caves with the new structures in adden. I've found this datapack but it makes some caves go into the void https://modrinth.com/datapack/no-generation-y?version=1.21.3
To be clear, in the surface I want the mountains and structures of the newer versions, in the caves I want the max height to be y0, to have the new structures and the deepslate