looking at an older house in Las Vegas (built in the 70's). the house has a flat roof and 2 rooftop ac units. It appears that the house originally had only one unit, with the second unit added later. The issue is that when they installed the second unit they installed the ductwork in the ceiling of the kitchen. the house has no attic so they create a drop ceiling for the duct work. The end result is the kitchen now has a 7' ceiling. My question is would it be feasible (and advisable) to remove the ductwork from the drop ceiling and relocate it to the roof (adequately insulated if possible)? I know no prices here but wonder the ballpark cost of such a project?