I got the stuff to build a rf offsett, my cc is round pipe 20x60 fb is 20x24 round pipe, I figured th smoke stack to be 6 in round 15 in long. Intake 10 wide 3 high , fb to cc opening 12.39 half moon or 8.7. Round . Do those measurements sound close , an on my fb to cc opening I think I read if using a round fb to cut out like a upside half moon would that work.
