Filling small pitting in metal / prep

['70 C/10 SS500]

I have a used valve cover that was pretty nasty when I got it. I sand blasted it hoping it would clean up pretty good. For the most part it did but there is some medium pitting on one side that I'd like to fill before I paint it so that it will have a relatively smooth finish. Is there any EASY to apply fillers or glaze (I really know next to nothing when it comes to this stuff) or something else that perferably doesn't need a hardener that I can use to fill this pitting? I've had very frustrating results with PPG acrylic filler, I can never really get it to harden, it's always soft and doesn't sand worth a sh@t, it gums up the paper! Any help would be appreciated!