Danielle, hey your job sounds pretty cool from here. On those wheels ... I am ignorant about the pregens but- At a glance I would have said they were aluminum. But the rim appears to be steel, so maybe the center is stamped steel too. I'd have to look at the backside to see how they are made. The script is awful sharp for a stamping, looks like a casting from here which would mean aluminum. Steel has to be protected immediately after blasting and cleaning if not also sanding.
Before anybody goes technical on that (I could help you with the OE color but yeah I would use engine paint or something, just silver).
My primary input for you, and mine is not often popular in the wheels department, is why do you want to put those on something that already has torque stars? I don't understand. I don't like them, don't spend another minute on them is my advice. Lets see the Torque Stars again if I missed a pic of problems with them. I'm currently spiffing some of those up one by one for mine.