I just installed a full stainless steel liner yesterday It was not that hard. But on a single storey living room that tends to be the case. Two storey houses could have a dog leg or whatever else in the chimney to make your day hell.
You must ,must strongly consider using a liner with an insert . Just shoving an insert into an existing masonry chimney like they did back in the 80's, is bad in 2 ways: lots of creosote buildup as the smoke from stove cools in the firebox which =chimney fire waiting to happen. And a proper sized liner will make the insert draft properly and burn more efficiently.
You must ,must strongly consider using a liner with an insert . Just shoving an insert into an existing masonry chimney like they did back in the 80's, is bad in 2 ways: lots of creosote buildup as the smoke from stove cools in the firebox which =chimney fire waiting to happen. And a proper sized liner will make the insert draft properly and burn more efficiently.