If the block has been milled down it wont be there or barley left. I really doubt that the block has been decked. Its directly behind and under the alternator. If you need disconnect the battery and swing the alternator out of the way. Loosen the bottom alt bolt, remove the top one, take the belt off, the alt will be loose enough to turn it left out of the way. Get some carb cleaner and a rag to wipe the pad off to see if there is anything stamped.