Hello again Alan,
I have been using a couple videos on YouTube as a reference for my restoration project. Both are regarding the Sun XXIII (now Suncrest) which is a near sistership to the Sun XXI. One is entitled 'A Video Tour of Suncrest', and the other is 'The Brief History of SUN XXIII'. Perhaps you have already seen them. Suncrest is now berthed at Trinity Buoy Wharf in London, I believe, and hope to visit someday. Best of luck with your project.
Cheers,
Ray