While not a '73 owner, I am familiar with these wheels from ordering some of them as parts required on jobs at our body shop. Ford used the same wheel on the '73 Maverick and Mercury Comet.
These wheels, both production installed and service parts, were not polished or clear coated. According to a fellow forum member David (Carolina_Mountain_Mustang), these wheels' OE finish was the result of high-speed diamond tooling.
If not concerned about originality, I would polish them and treat them to good-quality aluminum wheel polish/wax. My favorite is Mothers Mag and Aluminum wheel polish (P/N 05101), or you may want to use a brand you've had experience with.