The CMC binding posts arrived today and are now installed on my Sansui, along with some internal rewiring.
Best of all, I attacked them with a file and can confirm that this particular model (CMC 858-S-CU-R) is pure copper - no brass to be found! Likewise, the 858-L-CU-R, 858-S-CU-G and 858-L-CU-G (S and L denoting short or long, R and G denoting red copper or gold plated) should also be solid copper. I will post some pictures over the coming days.