Feedback wanted on Possible Kiln

I woke up this morning with a plan in my head for a simple wood-fired kiln, but I need to bounce the idea off of some potters more experienced with building kilns. I constructed the prototype above this morning. The idea is that the kiln climb up a slight hill and consist of chambers, each one able to hold 24 x 24 inch shelves with a space between the shelf and the next chamber for possible side-stoking. Each chamber rises six inches above the previous chamber. The hole in the wall in the above picture would be filled with a half block. Four 27-inch refractory block would serve as the roof of the kiln.


Here's a picture showing the ceiling, one shelf, and the floor of the next chamber. The picture is taken from what would be the chimney side of the kiln.


Here's a shot from the other side (firebox side) showing the two floor levels of two chambers.


So the idea is to lift and remove the 27-inch block in order to load and unload the kiln. They're quite heavy, so I'm kind of wondering if I'll get tired of that.

Two questions:

Will the walls buckle in or out after repeated firings?
Will the 27-inch block warp, or worse yet, crack from the stress? (I could always flip them every firing. I'm not sure if block like this are designed for what I want to use them for.)

The inside width would be about 25 inches, leaving just an inch for the 27-inch block to catch. The height of the prototype inside is about 25 inches.

I also have quite a few soft brick, and I could design "lids" for the kiln out of these. I know wood deteriorates soft brick, but there are protective coatings I could use.

What do you think?