Sandblast will be good, you wont need to sand it or anything after you blast it. after that, yeah, go ahead with the vasoline like customz said on the letters, if you want them to stay aluminum colored, and then go ahead and paint the cover. i have used a bunch in the past on my buddies cars. the BEST, i would have to say is the crinkle black and red. they end up looking the best(IMO) in the end, and look pretty OEM.

my buddy got the black crinckle paint for BBQ's and stuff (said BBQ's on the spray bottle) and sprayed it on his car a little less than a year ago, and it hasnt chipped or anything, so you can use that too ( i recomend it the most out of the rest). we go that paint at NAPA