I have a new to me house, that has a fireplace that was used for woodburning, but the last owner ran a gas line from in the basement and into the box for a gas logset. They came up through the ash dump with the gasline. I have removed the gas piping and will not be using the ash dump as they also blocked off the cleanout in the basement. I bought a cast dump cover but it is too small to cover the opening in the firebox. Could I possible high temp cement a piece of 16ga steel over it? Maybe with firebrick? But the steel would be way easier...thanks