removing a crumbling arch from a brick fireplace

We have a victorian property that had a really ugly brick facade added to a fireplace.
Having reomved this we have now exposed the original brick and it is sadly in a poor state. the brick arch at the top is collapsing and looks like the bricks in the middle section of the arch have been chopped down in size.
We intend to put in a wood burning stove and will likely hide all the brick work with a new stone surround.

The question is should I remove the arch and replace it with a lintel?
If so do you have any tips on type of lintel and how do I ensure that the bricks above don't fall down when I remove the arch

Thanks

Kevin

Last one I did I just knocked it out, your chimney aint going to fall down because of it. Stick a lintel above the arch. The cheeks looks substantial enough to bear the lintel.

Use a prestressed concrete lintel. Nothing is going to fall down as you can see the arch has dropped already therefore not holding anything up; it doesn't look original either.

Collapsing!!

Considering those soldier headers in that arch have had the b'Jesus knocked out of them, i'd say the arch is holding up ok.

As stated, use a p.c.c. builders lintel where and when you need it.