I think Vince at Great White Aquatics (fishguy69 on MASC) used to be able to order in a whole new top frame with the center bracket. Other shops may be able to order it as well. If you are going through a tank restoration, and you are going to the effort of polishing it up with cerium oxide I think it's a fast simple fix that will provide piece of mind for the long term. Especially since you just had a flood, I'd be weary of having another down the line. Saltwater weighs 8.6 pounds per gallon, so you are looking at over 1000lbs of water sitting behind that glass.
Just something to think about, I'd hate to see you get back up and running only to have another failure (like a seam rupture).