78 Jimmy rust

[Jimmyguy]

Hello I have a 78 GMC Jimmy and the ole cancer has gotten to her I have begun to fix some of the rust in the bed area. My question is has anybody here ever used POR 15 and can you use a spray in bed liner over POR 15. As I intend on spraying the hole inside of the truck. You can see my rust at Ole Rusty this site. Ive grinded down the rust in the bed area and primered over it but a friend of mine told me about POR 15. There is a hole in the driver side floor pan Im thinking about a fiberglass patch. Thanks in advance.