The MHRA Style Guide Online
A Handbook for Authors and Editors • Third Edition
From Chapter 2, 'Spelling and Usage'
The spelling of quotations is always that of the book or edition referred to. Note, however, that in quotations from early printed books the forms of the letters i and j, u and v, the long s (ſ or ſ ), the ampersand (&), the Tironian sign (⁊), the tilde, superior (superscript) letters in contractions, and other abbreviations are normalized to modern usage unless there are good reasons to the contrary, as, for example, in full bibliographical descriptions.