Alright, they are on 2:1 ratio, first I'll convert them to typical 1:1 like your walls. However, I think you got the wall shape just right on your own in the last pass. If we consider only the shape it just needs some tiling tweaking. I also agree on the shading plan as you described, that is how I would do it.
Regarding the new texture, however, it is quite neat, if a bit pillow shaded, but it looks more like some sort of alien biological tissue/hive thing rather than rock, I am afraid. It would look cool on a sci-fi setting

. I cannot give much help with that rock texturing, sorry. Natural textures are a pain to me and I am currently studying them exactly to close that knowledge gap.
Edit: here you go, it is not much but I hope it helps, i was easier to make a new one to match your stuff. These are Tiled ready, just load it as image source and set the terrain tool using the blue tips above each tile as a guide, they should be self explanatory. Notice you have uncomplicated internal corners because your top is just black, you go with weavy diagonals you might have to sculpt the internal corner tiles to fill gaps. Remeber to set the tileset file to have 16x64 tiles, margin16, spacing 16, but use them on a 16x16 map, and set draw order to be right-to-left/top-to-down. I think you got it pretty right on your take:
