Just curious, why don't you think yours is correct? Is it an original one or repro? Originals I believe are made from ABS plastic, repros I think are made from fiberglass. Look in the hole for the mounting brackets to see what material it's made from.
'71 style "gull wing" go wings I would imagine are pretty standard, unlike the '70 style which looked similar to the Ford versions but the Ford versions were a bit narrower and on shorter pedestals I believe. Omly Mopars had the '71 style wing to my knowledge so they should be pretty standard sized, IMO. Could be wrong...