I understand you can paint Por 15 over surface rust? Is it safe to do taht or should i just strip the rust totally down.

visit their website and review their recommendations but light sanding and then painting with the POR stuff works well. Use the 'search' function and type in "POR" and you will get tons of info. here as well.

POR = Paint Over Rust

Doesn't por have a rust preventative you put on the rust first. I mite be wrong but I always thought they did.

POR painting is a 3 step process. 4 steps if you top-coat it.
Sand or brush off all loose rust and scale. Wash with Marine Clean. Treat rusted area with Metal Ready to etch the metal. Then paint the rust with the POR paint.
The Metal Ready is a zinc phosphate treatment.
http://www.por15.com/4STEPSYSTEM/tabid/187/Default.aspx

I like the rustbullet... It has worked good for me... only comes in gray tho...
check out www.rustbullet.com

My buddy used Rust Bullet on his restoration and I was impressed with it.
It's pretty thick, like POR and it seemed to stick like glue. He spray painted over it (engine bay) and it came out great. He painted everywhere with it... not just rusty areas.
It's full of iso's just like POR so it'll give you brain damage just the same.
;)

On my corvette frame-----I sanded the frame down to get the scale off of it. I made a few repairs wiped it down with lacquer thinner and then painted the stuff on. When you use this stuff be careful with it and dont put the old back in the can. The frame looks awesome. Be sure to read the directions on the can.

But evidently you can paint over rust I.E. POR!

Good Luck

...and wear gloves!