I was looking at this G5 spoiler last week.... I think they are close but not exact.
You can make it work, you'd need to fill the old holes and drill new ones... making sure it's centered too. lol
I guess we could ask someone in the G5 forums to measure thiers.
and the 99+ GA wing measurements..
rear holes 32 7/8" and the front two are 38.5" center to center of the bolts.