I braced the row of fire bricks ar a 30 degree angle. I then wegded brick ties into the mortar between the bricks and tied those to pieces of rebar that extend behind the side rows of fire brick. I filled all that in with concrete. After the concrete dried, I completed the shelf with mortar and made a concave shelf. Luckily, when I removed the bracing, everything stayed in place.
I cut a length of angle iron to go across the front where there are no blocks. This will support the structure above.
My friend, Mark, and I built a wood frame for a vault. There is a smaller frame inside. The inside frame is 4 inches smaller to allow for concrete and reinforcing wire. My neighbor, Andy, came over to held with the concrete casting and bracing of the frame.
It took ten 80 pound bags of concrete to fill the frame.
I removed the frame today and it looks pretty good. I will eventually face the entire parrilla with stone from my property.
Here is a section where I have attached part of the stome facing ( and the gargoyle sconse to hold my beer).
I will still have to put two more course of block on the top to get a good draft. I also need to get the metal parts fabricated: the cooking surface, bar, chain and so forth.