Fixing surface rust/new parts questions

[68longhorn]

I have a 86swb that is starting to surface rust on the roof. The paint was thin there for years but finally started showing rust. What's the best thing to do, I am not ready for a repaint, just want to prevent rot. I was considering scuffing the roof and spray painting. Will that work or would it be wiser to sand it down bare and spray paint? Or should I use rust converter spray?

Also I will be replacing body panels, do they come painted or do I need to paint them to prevent rusting before a full respray?

[Dayton601]

Kind of going through this myself right now with a total rebuild of my 81 c10, what i have been doing is hitting the area with a wire wheel, using the smaller type wire, not the coarse ones, getting it as clean as possible, then spray it with ospho, let it sit for several minutes, then either scotch bright it or take the wire wheel to it again, then spray ospho on it again and let it sit for several hours, you will see it urn a little black where the rust was, spray it again with ospho to reactivate what has dried, then I would wipe it off, then wet sand it with 600 paper, dry it off, if it sheen's over with a little orange rusty looking film, some times that happens before you can paint it with etching primer or epoxy (2 part paint), then wipe it with a lint free rag with a little ospho, if its thin enough it should dry quickly, and the rust color will be gone, hit it with the scotch brite or just spray over the ospho, should be smooth by now if you sanded right,(according to directions on ospho it can be directly painted over), I just never liked the powdery look it some times has after it has dried for a long time, if it does that then re activate it and clean it all over again, its worked so far for me,

[Dayton601]

Here is an inner fender I'm working on with a little rust, used ospho then wire wheeled it, let it set overnight, then ospho again, then washed it off and you can see the flash over with rust Im talking about, you might have to hit it a few more times with wire wheel and ospho, rinsed it off, then i wipe it down with a clean rag with ospho again and see how it cleans up, used a little de-greaser then shot some etching primer,

[68longhorn]

That is pretty cool. I will check that out