In the Spanish version of the article on the wikipedia page is a link to a digital version in highest definition: https://digi.ub.uni-heidelberg.de/diglit/ercolano1757bd1/0005
Don't forget to check first: Volume 5 1767 Bronzes from Herculaneum and region, engraved and described - Part I: Busts . (I already did the mistake to start search in book I)
https://digi.ub.uni-heidelberg.de/diglit/ercolano1767bd5/0115