Not only is the papacy the longest continuously operating organization in western civilization, but, in true western fashion, there is a bureaucracy attached to it. Like all bureaucracies the papacy is fond of paperwork and lists, and since the third century has kept a list of every pope. Beginning in the renaissance it has been known as the Liber Pontificalis, the book of popes.
The quality of the entries has varied widely, everything from merely a name and regnal dates, to brief lives that include some background information and deeds performed while pope. Most of the lives were written during the lifetime of the pope, or immediately after their death. We are fortunate to have that sort of detail available for the eighth century, although the details vary considerably.
We have two English-language source for these lives. King translates some of the lives. He gives a brief introduction to the Liber, and limits his selections to those during Charlemagne’s reign. If you want to go full Liber you need to go with Raymond Davis. He has two volumes out that include the 8th century. The first covers the list of popes up to 715, and the second, The Lives of the Ninth Century Popes, ends with the reign of Stephen IV in 817. Davis provides some background and a detailed look at the manuscripts, modifications, editions, etc. Which is amazing, if you’re into that sort of thing, but it gets a little detailed, shall we say, for my taste. He also offers commentary on the individual lives, anything from fifteen pages for Hadrian I, to just two pages for Gregory III.
Reading the actual lives of the popes is fascinating, both for what they say (and how they say it), but also for what they don’t say. The life of Zacharias (741 – 752) doesn’t mention authorizing Pepin’s deposition of Childeric III and his own elevation to the kingship.
It is to be expected that the lives of the popes would focus on matters spiritual, not temporal. But there is a lot of focus on church repairs, and detailed lists of chandeliers, windows, and other improvements. The writers, all anonymous, chose what they felt was most appropriate in each instance.