Ram 1500 with an axe...
Minister of Fire
Well if it were me, I would go with an insert. I'm not an expert but I think the lopi dealer did not explain correctly to you. I feel that you will definitely need a 6" ss pipe going from your insert out the chimney. Now you have something very unique, that masonry cap. What you are gonna need to do is extend and secure the new ss pipe 6" above the chimney top, underneath your permanent cap, then you are going to have to seal off any extra space between the new liner and the old masonry line up where your ss liner protrudes your masonry liner. Do you understand my point? If you were not to use a proper ss liner connected to your insert, back smoking would occur and it would be coming back into the house through the surround edges. You seem to have something very unique, I would not put in some sort of hokey contraption if you are trying to get heat out of it. I would get the biggest insert that would fit and looks pleasing to you.....my opinion and again I'm not an expert. Before I got my insert, I was looking at fire racks with blowers, cast iron plates to line the firebox, etc, don't waste your time or money on contraptions, my insert gets great heat and is medium in size, I'd prefer bigger but the look I get from my montpelier is at the top of my needs list....anyways good luck and keep trying to learn