I have 2 fireboxes that were lined by the previous owner with fire brick and have vented gas logs, but this makes the fireplaces very small since they are only 24 inches wide to begin with. Underneath the firebrick is the bare brick masonary, 100 ys old. It is in good shape but was wondering if there is another way to line the firebox without firebrick, especially since the firebrick needs to be repaired. I will not be able to use a pre-fab ceramic liner because of the dimensions of the fireplace. Can you use/buy pieces of ceramic liner or can you just cover the bricks with a layer of heat resistant plaster? It seems that was done at one point in the back of the fireplace. Thank you for your advice.