just bought a new 4 peice electrical kitchen set which also included an over the range microwave. I'm trying to install it myself. the origanl vent in place for the former hood is about 6 inches lower than where i need it. i follow the template given, draw the outline for new hole and snip off at the dry wall. now exposed, is see a gas line in the way. no treally troubled it's there because i want it gone. i got a new electric rang in place with all the right connections ready to go. i know my attic is "gas line central". I've identified which line goes to my oven, my problem is i can't shut that off without shutting everything off. how do i seal that specific line off and avoid a gas leak being my first question and secondly, how i push this new vent hole straight outside and seal the old one?