dutchwest 2462 install questions

Hi all, i recently bought a used dutchwest 2462. I was wanting to install in an existing fireplace but it is too tall. So my options are to go straight thru the ceiling and the darling wife hates that idea. I have had the chimney swept and inspected yesterday and the 7x11 clay flue tile are in good shape. If i can get through the fireplace stone(geode) should i use the existing flue orstainless flex. Or should i try to notch the top of the opening and exit out the rear then through damper? Hopefully 'm explaining this clearly. I havent built the hearth yet so i know it will be much higher.

26 to 27". There is steel along the top i guess as a form when they put the stone on.

this is the steel i was talking about begreen.

Begreen, the old stove is in decent shape but needs a cat and rope seals. So what do you think about going above the mantel and trying to pop through there to get to the chimney?

Woody stover, there is only a thin layer of brick down there now. I believe the 2462 is 33" to the top of the flue when rear exit. I also have a 2461 thats smaller, shorter. Both were bought used.

I had those dimensions on my phone but cant find them, maybe deleted. Im at work now so I can't measure. If i went with an insert, probably new.

House is an old 2 story with heat pump. 1680 sq feet. 8 ft ceilings. Realisticly around 1200 sq. Ft.