Liner installation concerns

[Cold feet. Warm heart]

Finally ready for a new stove but have installation concerns. I'm hoping for some guidance.
Removed an old slammer and ready for a stove. 25 ft brick/ masonry 8*13 chimney was deemed too small for liner and recommended breaking out the flue tile. After some pricey quotes we decided to rent a tile breaker and diy. Everything went fine until we got to the bottom course of tile which was backed with concrete. There is no breaking it out. In addition I now see the the transition (smoke chamber?) from the chimney bottom to firebox is only 7" wide.
Is there a problem with compressing a 6" insulated liner in that area? I'm guessing it will measure at least 8" once we insulation is added. Is compression a safety concern?
We decided to pay for the installation to be sure it's correct. Just want to make sure I understand what that entails.
Thanks for all replies🙏

 

[EbS-P]

What does the damper look like? I completely removed my damper frame (and damper) and could almost stand up in the smoke chamber from there I could have removed the last course of tile.

 

[Cold feet. Warm heart]

What does the damper look like? I completely removed my damper frame (and damper) and could almost stand up in the smoke chamber from there I could have removed the last course of tile.

We took the damper out years ago while using the slammer. We don't have much room up there to work. I had to lie on my back and shove a "t" stick up there to get the measurements

 

[bholler]

We took the damper out years ago while using the slammer. We don't have much room up there to work. I had to lie on my back and shove a "t" stick up there to get the measurements

Take more out and get up in there with an electric or air powered impact hammer with a chisel on it. Yes it sucks but it's what needs to be done at this point. An easier option would have been an oval liner.

 

[Cold feet. Warm heart]

Take more out and get up in there with an electric or air powered impact hammer with a chisel on it. Yes it sucks but it's what needs to be done at this point. An easier option would have been an oval liner.

Thank you so much for your reply. You mean break up the entire smoke chamber?! Because that also is only 7" wide. We have to remove that? Wouldn't we need a mason for that, and $$$$
Can we squish the insulation in that area below the chimney flue? Unsafe?
I really do appreciate your willingness to help me sort this out. We are doing our best at 70 and 80 yrs old. I could try.

 

[bholler]

You mean break up the smoke chamber?! Because that also is only 7" wide. We have to remove that?
Can't we squish the insulation in that area below the chimney flue?

Yes chisel out enough material to make it fit