Im thinking the chimney on top of the roof its the major issue then the
cost of the stainless liner for the chimney. You could get a quote if
you want but I dont know a guy who would touch it with a clear
concience. And you could be looking at a $5K project if you did find
one. You gotta save a lot of heat to justify that plus the stove. And
the guy that owned the place before you may have some hidden insight
why he did a permanent end to the chimney.

My recommendation is plug the fireplace nice and tight with a chimney
balloon low down by the damper or just above the firebox, so you dont
loose heat up the chimney. Then put in there a nice candelabra or
decorative birch log stack and just enjoy it as an interior design
piece. IT would be an uphill climb to resore it back to life again.