I've decided that my XL600 rebuild project probably deserves its own thread, so I can stop clogging up this thread with progress pictures!!
I will post general progress updates and pictures over there in the new thread, and will continue to post questions and queries here. It seems to me that that's probably the way it should be.
As usual, many thanks to everyone here for all the help.
Hopefully, with the holidays now more-or-less behind us, I can get back to being a little more focused on the build.