Installing my woodstove in my new home and worried about the siding issue I see people have. I have 6 inch selkirk thru the wall setup. I can't find a Standoff box so I can J-Channel around it and reinstall the siding. The Chimney pipe has a 8 inch outside diameter. Anyone done this? Know the part number? Is this it says it has a 8 1/4 inside diameter.