making trees from an existing datapack taller

I was messing around with a datapack called Arboria: Biome Enhancement, and decided to copy some of its features into my own datapack (I'm not publishing it so I don't think there's any issues with borrowing a few things), one of which is the spruce tree type. What I don't like about those though is that the trunk is too short at the bottom, basically preventing villages from spawning. However no matter what I do to the config of the trees, something always goes wrong - either some of the leaves are flying or the trunk cuts into them. How do I increase the height of the base of the tree, while moving the rest up (preferably by 3 blocks)?
I attached the config file of one of the trees
The branch/branch_set related files have no height-related numbers