Post the pics and let me take a look. Depending on the age and type of resin, CA glue usually works best in my book. I've done several repairs to older cars that way. Let's see how bad it really is though.
I've got the same Ranchero body and planned on making it and a panel someday. The Shelby American Collection museum has the original Shelby shop panel that is all GT-350'd. Very cool.