Some Rust on Front Floor Panels

I second sand blasting. A wire wheel will almost polish (burnish) the metal and give a surface that is not desireable to paint over (it will eventually peel). If you can't sand blast, use a DA with 80 grit, or a 4 or 4.5 in grinder, this will give you a much better finnish for paint to stick too. I would also use "epoxy primer" and then a good sealer (color of the car) over that. I am not a fan of POR-15 (paint on your own risk)
Just my 02.

barracudadave67