Planning on making my old fireplace work again. Insert? Firebox? Rebuild?

[gg1]

I have a pretty large fireplace that is a little odd in some ways. Has a metal floor that dumps ash to the basement clean out. A big metal plate in the back. I was told the brick isn't "firebrick". The opening in front is 48" wide by 36" high. It is 28" deep at the bottom, but 19 1/2" at the top. Here are some pictures to help. I don't like when there is some surround that covers the stone, so I like a flush look, or just go with an open fireplace, but they are wildly inefficient. Ahren-Fire was proposed by two companies if I want an open fireplace. Approx $9k US. I certainly feel I could line this myself and get a mason to fix issues, but no firebrick? Any ideas? I like clean and more modern, but the fireplace itself isn't "modern" looking.

 

[begreen]

An insert doesn't need to have the factory surround installed. Some can be installed with a custom surround that fits just inside of the fireplace opening. Or some just leave the surround off completely. The fireplace is tall enough that a freestanding stove could go in.

Are there side vents on the fireplace?

 

[gg1]

An insert doesn't need to have the factory surround installed. Some can be installed with a custom surround that fits just inside of the fireplace opening. Or some just leave the surround off completely. The fireplace is tall enough that a freestanding stove could go in.

Are there side vents on the fireplace?

No vents on the fireplace. Here is a picture of the chimney if that helps. Thanks for the reply.