I purchased your flanging tool and panel adhesive a while back, and am about to start my project of replacing rusted metal on the rear quarters of my 89 Acura Legend sedan. I’ve fashioned cardboard patterns for the replacement panels …cut out the old rusted metal, and now I need to buy two panels of sheet metal, about 18 inches wide by 40 inches long. Questions: what gauge metal should I buy to match the original body metal? Should I buy “plain” or “galvanized” metal??