I'm interested in finding out at which point the classical word order of Latin, which often placed words in order of emphasis, was replaced by the more modern format of: subject-object-verb. (Sorry if this only applies to English medieval texts)
Sorry, are you saying that you think classical Latin word order was just 'free', and more modern Latin defaulted to SOV?
That's not really correct. Classical Latin often defaults to SOV, with variation. Inflected languages use syntactical order for different purposes than, say, English. Which your question seems to be well aware of, which is why I'm puzzled by your question itself.