Check in the "Tech Articles" section of this site, and you'll find:
http://www.pelicanparts.com/techarticles/mult_wheel_refinish/fuchs2.htm
http://www.pelicanparts.com/techarticles/mult_wheel_refinish/fuchs1.htm
The finish was a bare-metal look (not polished, I don't think) on the raised parts of the Fuchs, and a sort of milky-white anodizing on the recessed parts.
[edit--]A number of the four-bolt wheels wound up with black-painted recessed areas. But those seem to have been done by the dealer, the importer, or one of the car's owners. John Larson has mentioned that was one of the jobs that the "lot boy" at the dealership he worked for did in 73+.[--edit]
...Unless you're talking about five-bolt ones, in which case there were a bunch of different finishes.
--DD