Bought a 1950s ranch which I’m gutting now.  There a big chimney which is in pretty good shape. 1st Flue is being used by Old Fired Hot Water Boiler, 2nd (middle) flue used to be for some kind of oven in the kitchen which was removed and bricked over. 3rd clay Flue will be used for a new Wood Stove in which I’ll add S/S pipe to help preserve current chimney flue. Previous owners capped the 2nd flue with damper that sits on top which is in good shape but I’m thinking of 3 options and would love to hear opinions: 1.   I’m gutting the house so I can recycle the mineral wool which is in the walls and fill the flue in order to deter rodents/bugs while at the same time maybe create some energy efficiency by insulating? 2.  Fill the 10 foot flue with cement to strengthen the entire chimney? 3.  Install a big antenna on a 30-40 ft pole of which 10 ft would sit in the flue and be hold in place by cement.  Obviously this would create a very strong antenna pole but could lightening strike and potentially compromise the integrity of the whole chimney?