You’ll find no text in ancient Greek that puts diacritics (accents or breathings) over capital letters: they’re always set before the capital letter.
Diacritics entered ancient Greek in the Hellenistic period and have been written this way for about 22 centuries. I see no reason to go against this tradition.
This is the relevant part of the Greek Extended Unicode block:
I found a modern citation of the same book:
You can note that the breathing is placed correctly before the A, in your picture
