[1.7.10] Prevent block placement above a certain block?

[61352151511]

I don't know how to word the title correctly. Basically I have a block with the dimensions being 16x26x13 When you look at it the bounding box is the correct size, however that's only when you look in the default 16x16x16 area. If you look at it at the upper part the bounding box is not there. That's one problem I'd like help solving. The second part is that you can still place other blocks in the position above it, so only the top 6 pixels of that block will be visible. I want to prevent blocks from being placed one block above it so technically the block added will take up 1x2x1 blocks. If anyone knows how to solve either of these issues I'd appreciate the help.

[Draco18s]

Fill the volume with invisible technical blocks that do not allow replacement (and otherwise are treated as air).