Fireplace gas valve questions

I'm renovating and one project I have is to install a log lighter in my fireplace. Currently, there's a plastic-handled gas valve inside the firebox. Before I bought the house, I guess the gas company had come out to cap it. When I had my level 2 chimney inspection done, the guy told me that it wasn't safe to use it as-is. He said to either find the existing gas valve under the flooring or behind the mantel or get a new one installed. So I pulled the mantel off along with the flooring (I'm redoing it anyway), and I can't find the original valve. My questions are:

  • What can I expect to make this fireplace log lighter ready

  • Can anybody surmise what the story behind the original gas valve is?

  • Why is there a plastic gas valve in the firebox?

  • What is the concrete "box" around the brick? Is that original to the house? Is it possible that the original valve was sealed up underneath that?

https://preview.redd.it/f89x97x1j2ge1.jpg?width=1536&format=pjpg&auto=webp&s=21a364faa079033636329cc0f541296cf9e80bce

https://preview.redd.it/7gsi4mf4j2ge1.png?width=1026&format=png&auto=webp&s=2595833c9d59d45c31edd37d1b25201ca18d897f