Ok, still looking at this, and I see something. The photo from Billion and Trillions guy looks like this RH inner fender on your left: The Cars People (oldbuickparts.com) offer a part they call "Inner Fender Repair Panel 1970-72 Buick" which they want $145 for and it looks like this: To me this looks like an exact match for the rotted front edge of the 1968-1969 inner fender on the RH side by the battery...
The ‘70-‘72 patch will work on ‘68-‘69. I’ve not done it nor know the details but have seen it as a finished product and it looked good. Patrick
And since no one else did it, here’s Frank deLazare (sp), aka Biker Fox. He’s ‘Billions snd Trillions’. You’re welcome! Patrick
Got both sides listed, and I'm not far away for you. http://www.v8buick.com/index.php?threads/68-69-rh-inner-fender-well.358415/ http://www.v8buick.com/index.php?threads/lh-68-9-lh-inner-fender.254088/
After much time passed: https://www.v8buick.com/index.php?t...-inner-fender-it-doesnt-look-original.364612/