Dannibal,
As cfischer said it can be done by Delta in advance.
Ask for your desired type of seat (aisle, window) between rows 60-64.
Row 65 is only at the airport ...
Rows 66-69 are "premium seats" for those willing to pay 50euros for the guarantee to be on the upper deck (AF tickets only I think).
But you as Platinum (even on DL ticket, again!) have access to reserve a seat in rows 60-64.