Replacing arch with lintel, opening up fireplace

[Infole]

I'm looking to open up this fireplace, which was bricked up early 2000s. Will be installing a cast iron fireplace, but it will only be decorative and plan to plaster the wall around it.

Based on the plaster already removed, it looks like the arch is no longer sound? It looks like the arch has been filled in the center, and the bricks above it look cracked and potentially sagging.

I'd like to install a lintel, probably in place of the arch. There is 1.5 bricks either side of the arch, which I understand is sufficient for the lintel to sit on? Would I need acrows to support the brickwork above the arch, or should I allow this to collapse once the arch is removed, and then rebuild it above the lintel?

Is there anything I may have forgotten and need to consider? The property is early 1900s and I'm planning to use a standard mortar mix instead of lime, as it won't be visible. The arch spans about 85cm

 

[23vc]

Shouldn’t need acros if you’re careful
The arch looks like it’ll hold if you go easy removing the course below it for the lintel, if that’s where you want the lintel. Just needs to clear the new fireback.

 

[ree]

The arch is fine, no need for a lintel - to firm things up you could rake out & point the soldier bricks and the bricks above - and then just carry on removing the in-fill.

 

[Infole]

Shouldn’t need acros if you’re careful
The arch looks like it’ll hold if you go easy removing the course below it for the lintel, if that’s where you want the lintel. Just needs to clear the new fireback.

I had been considering replacing the arch with a lintel, but I've just had a proper measure and the fireback is about 75mm lower than the arch. It might therefore be able to fit a 65mm x 100mm lintel for support

 

[Infole]

The arch is fine, no need for a lintel - to firm things up you could rake out & point the soldier bricks and the bricks above - and then just carry on removing the in-fill.

I think my main concern has been regarding the 3 soldier bricks in the center - they appear to be half length, with a horizontal 1/2 brick having been added when the fireplace was filled in. Definitely will be raking out and pointing, as some of the mortar has almost completely gone, presumably either attached to the plaster I removed or fell out when they bricked up.