I recently bought a house that had an old existing wood burning fireplace. I decided to replace the fireplace with a new wood burning fireplace, but then convert it to gas. I wanted to keep the existing chimney which is double walled galvanized steel (outer) which is 11" on the outside and 8" for the inner pipe. My new fireplace has an 11 inch collar, so I was looking for a reducer to fit my inner chimney pipe. Is this possible? any issues with doing this? I haven't been able to find this anywhere so any suggestions to look would be great. It's Majestic fireplace with SL1100 pipe.