Besides having added more pictures to the original post, I've been experimenting with different strings.
When I picked up the guitar from John, he'd strung it with D'Addario Silk & Steel .011-.047, but it was a bit too rubber-bandy sounding, especially with my habit of tuning down, and even more so in open C tuning.
I got some GHS Silk & Bronze .012-.054, and while they had the tension, the tone was just not happening in this combination. The silk seemed to have muted the highs too much, and the vibration of the strings felt/sounded restricted.
I then decided to put on a set of D'Addario J-21 .012-.052 nickel wounds and THAT woke the guitar up for my particular set of needs.
It's a nice chase to take part in!
Best,
Howard Emerson