I have a few questions about installing blaze king sirocco 25. I have a pre fab heatilator fireplace at the moment. If I remove that pre fabricated fireplace and put concrete board on the bottom and had firebrick installed on all three sides from the concrete board up. Then the top is tin with insulation then another double wall insulated tin hood. Would this be sufficient for an install? Also would be putting new 6” flexible stainless inside my existing 8-9” insulation pipe. Or is the only option putting another pre fab in that would fit the sirroco?