I've done a little test sanding and it reveals good metal, in most cases the original factory off white. It looks horrendous, but it's just rusty "dust" mostly at this point. Can I sand and use some rust converter or POR 15, which I've heard about? Also visible is some kind of semi metallic hard factory floor liner, like insulation or reinforcement. It's glued on very firmly. Floors have no holes, bubbles, cracks. I'm putting in carpet and insulator. What to do?