Greetings from NE Kansas

This past summer I purchased a 63 1/2 Ranchero that was originally a 260 three speed car. Somewhere in its history someone replaced the original drivetrain with a 289 and C4 from a '66 Mustang. She's rusty and crusty but I've wanted one of these since I was in high school many years ago. If it had been a six cylinder, I would have passed it by. It needs a complete floor pan and both rear quarters which I have purchased. Now I need to find the metal inside the rear quarters, I'm a retired Industrial Arts teacher and a lifelong Kansan.