Here are the measurements from the gilled fender of my original cuda.
If you place trhe tape measure inside the opening on the gill closest to the door, the distance from the top inside to the rear edge of the fender is 7" exactly.
If you place the tape measure inside the opening at the bottom of the gill, that measurement is 5 3/4" to the rear edge of the fender.
I'll try to get a decent pic and label all of the measurements when I get time.