Hey Jeggert,
Thanks for cycling me on this one. No, I don't have those plans, but you reminded me to pull down a couple of old favorite books from my shelf to see if they had your answer. Not quite.
Looking at "Masting and Rigging the Clipper Ship and Ocean Carrier", "Sailing Ships Rigs and Rigging", and "Deep-Water Sail" all by Harold Underhill, written in the 30s, 40s and 50s, and reprinted in the early 1970s. Each of these has tons of the kind of material you are asking about, both generic detail and sail plans and specific ship drawings, but none exactly have the Thermopylae. However, there is a note inside the book jacket that "these and many more" ship drawings are available from Brown Son and Ferguson. I was shocked to see that they still exist and have a website, at https://www.skipper.co.uk/. I strongly suggest you visit that site and perhaps also look at Mr Underhill's books.
I had forgotten how much I loved those books, and it has been a joy to bring them off the shelf and remember my big plans for sailing ship models, 50 years ago.
Good luck with your endeavors,
Rick