Chromie asked if I could load up these pics to show you where rust can occur and that it maybe worth you checking it out.
"Here is a picture of what one can expect under the front guard to windscreen frame for rust and bonding failure.
The pictures are off a 1970 roadster right side which was showing no signs of rust, this was a precaution repair before we respray the vehicle "ALL C3 CORVETTE WINDSCREEN FRAMES RUST DUE TO DELAMINATION OF THE BONDING MATERIAL BETWEEN THE FIBREGLASS AND METAL FRAME, THEY ALSO RUST DUE TO POOR PAINT PROTECTION BY THE FACTORY AND DUE TO THE AGE OF THE VEHICLE"