Top and Side Textures for Slabs and Stairs

I was wondering if it would be possible to allow for top and side textures to be implemented for different block bases such as slabs, stairs, walls, and fences. I am trying to make a new type of block type called ashstone that basically reflects sandstone textures, except they are darker.

The only problem is that sandstone-like textures have different textures on the top, bottom, and sides of all block types including slabs, stairs, and walls, which is not currently possible without importing custom models and coding it in. The only downside to this method is that then these custom blocks can't be waterlogged and, not to mention, is a super time-consuming process for a mediocre result.

Thanks! :)