Hi everyone. I’m installing a Lopi Large Flush insert. I’m using a Forever Flex double wall liner. I have maybe 1.5 inches of clearance between the top of the appliance and the height of the fireplace. The manual says to attach the flue to the top of the appliance using three L brackets and drilling directly into the top of the appliance and the liner. I unfortunately don’t have that clearance, so I ended up making my own long L brackets, took the guts of the system out, and attached the brackets from the inside out: screwing the bottom L to the roof of the appliance. And the top of the L to the inside of the liner. I used the screws they provided to attach to the roof of the appliance, the same used to hold up the pipes inside the fireplace. I then used metal roofing screws for the inside of the liner. Are there issues with screwing inside the appliance on the roof? I sealed the liner to the appliance very liberally with Mill PAC Black. I’m just wondering if the L brackets and screws can take the heat. Also, is mill pac black a cement? Or is it more like silicone?