I did not see any used fenders here for your ride
https://frankspontiacparts.com/usedparts/gtoparts.htm
You should call him to see if he has a line on a pair,or to be first on the list to call in case he gets them.
He is an honest guy who wont misrepresent his stuff. I have bought several things from him for my goat
Atermarket stuff aint the greatest
I did however buy a dynacorn hood for my 64 GTO and it is as close to perfect as you could imagine.