no, i'm all about saving a game if possible. but with the bottom falling out like that. I would assume the water damage is massive. Which means the transformer is probably assed, and rusted everywhere. If that's all the problem is, yes it can be saved. If everything else is assed up inside, then you are better off parting it out.
as for the decals. It has nothing to do with purity. It has to do with decals are fragile as shit. if you squeeze between 2 games that are decalled, your belt will put a nice long white streak across the cabinet without much effort. They are terrible when it comes to durability. So when I see someone take a cabinet is fairly nice shape, and decal it, instead of just touching it up. they ruin the cabinet. I value it much less. At that point, I would not buy that game unless it was dirt cheap.