So i was thinking of doing a alcove and putting a BK King in there. I see it uses a 8" vent and class A above the box to the top of the chimney. I had a ZC gas and now have a PE Super. My question is will the 8" class A fit up top threw the existing chimney? i will be removing the ss 6" liner currently in there. Or is this a dumb question because i need to go up there and measure?, sorry i wasn't sure if there was a standard or not when it comes to general chimneys. Or am i gonna have to modify up there outside. Also, when i put the ceiling box in, when i am installing the pipe when on the roof, do i just keep connecting them until i have enough sticking out? and will it be hard to connect to the ceiling box since i will be about 15' from the box do i just feel until its inserted and then just twist?