Ok....Job might be a little more involved.
You have to determine if you have the 1970 Cuda brackets or the 1971 Cuda brackets.
The 70 brackets "fit'' the contour of the lid only in one area so it will be easy to determine the approximate location of the wing. The 71 brackets will be more difficult.
BEFORE you drill, assemble the wing and use it for measuring between the left and right uprights. Sometimes the aftermarket wings aren't exactly the same as originals.
Can you post a picture of the underside of your deck lid ? You may have one wing cut-out in the correct location already.