An easy-to-find reference is the Monogram/Revell 1/24 '64 GTO, since the cousins share the same greenhouse and many components, it is a handy 3D guide, as Monogram did a very nice job capturing those shapes. Revell 1/25 '65 Chevelle did to a decent standard.
The other thing that caught my eye, and this may just be a trick of the eye viewing a picture of a picture so to speak, but the quarter panel character line seems to be casting a shadow, indicating that is a raised " bead" ( for lack of a better term). It actually mimics the profile of the larger line that runs the length of the car below it. It is just a shorter, smaller curving step, and would catch the same highlight as the other body line. Also, at the rear end, where it is shown turning down and creating a small squarish "cove", sort of like a smaller '64 Impala quarter panel, it should NOT do that! The upper line sort of fades into nothing just before reaching down to the mid-body line; very subtle.
I offer this in genuine wishes for the printed model to be as accurate as possible. You have hit upon a car that is a personal favorite!