OP,
Hans Moust is very likely the world authority on Guilds. I’m linking his website below.
I had a very similar question on exactly the same guitar a few years ago. I contacted Hans and had an extremely nice email exchange of photos and information. He is compiling Guild data, and I am certain he would enjoy hearing from you.
I eventually traded my exc + X700 Stuart for a mint Gibson LP R6, straight up. Both parties were happy. It has been 2-3 years. At that time we landed on approximately $2750 as a value for both, that being the midpoint of the 2500-3000$ range.
They are great guitars, and undervalued relative to comparable Gibsons. If you want to consign, I’d think about Archtops.com. They have mixed reviews, but they will get it done fairly quickly imo.
You could also check out Letstalkguild.com, if they’re still out there. Lots of closeted Guild archie fans.
Good luck. Here’s Hans Moust website:
http://www.guitarchives.nl/guitarsgalore/