[gtoformula]

Plasti-Kote makes a paint called Rebuilder's Cast Finish Gray #285. I have used it on cast suspension parts and found that it adheres well, dries quickly and it resistant to petroleum fluids. It would look good on your wheels.
American made the 200s in the 60's and early 70's ... these were the equivalent of today's Torque Thrust wheels. They came in three styles: a dark matt finish, light cast finish or polished. You could use any of these appearances and be correct. The ET five spokes were a dark finish on the spokes with a machined finish around the outer rim area.
Before factory mags we would sell tons of these aftermarket wheels and they only went for about $50/wheel (more or less depending on style and manufacturer). The good news was the price back then ... the bad news was that many a factory sport wheel went into the trash due to replacement by these old mags.