I think the trick to doing this replica is in finding a suitable "close enough" book to start with. Then adding the inserted letters, etc shouldn't take too much time. Looking forward to seeing what you come up with...
In 2020, I did extensive research on this and have found the exact edition of the book shown in the film is "HERODOTUS" by H. F. CARY. The printing plate used to print the version of the book shown in the film is from the 1872, 1885, or 1891 edition published by George Bell and Sons of London and printed by William Clowes and Sons, Ltd. in London. It is a total of 613 pages and often includes up to 24 extra pages of advertisements. There are many versions of the Cary translation of Herodotus but I have only found that the version I've listed above are of the exact version as shown in the film. Avoid the American printings as these do not match. The novel of "The English Patient" says that Almasy carries, "his 1890 edition of Herodotus' Histories" but the version shown in the film can only be 1872, 1885, or 1891. I have not found ANY version printed in 1890. I ordered many versions from old bookshops in the UK through www.abebooks.com. I had a professional bookbinder try to recreate the outer jacket to look like the prop in the film because the correct editions above look nothing like the book in the film from the outside. I had limited success here but it what I wound up with is at least passable, right down to the elastic strap to hold the book closed. I filled the book with still images from the film inserted at appropriate sections of the book to make my "prop" version and even did some photo editing to stretch Katherine's paintings to look like the inserts shown in the film. See attached picture. I'm happy to share the files I created to make mine.