JA - during my 20 years I don't remember any silver in the mix. For one thing, 'wire' wasn't really a thing yet in the early years. And also, we had very little spare cash, and 'wire' seemed over-priced for our sensibilities. The price of silver was a bridge too far. We were exposed and traded for those Kimber super expensive and magnificent speaker cables, but at that time those were copper. I've been told the later ("Black Swan"?) version, which became one of Jim's staples, may be silver, but that was in the 2000s. The Goertz that he used to develop the 3.7 was (I think) a copper version. (Someone on this forum may know for sure.)
Short answer is that from the mid 70s to mid 90s, silver wasn't in the picture. At that time we had found the 6-9s / aerospace wire which we brought to AcoustaCoil and Straightwire, which defined our approach to wire.
