Due to the peculiar nature of the Chinese writing system, it is difficult to assess the pronunciation of historical varieties of Chinese. In order to reconstruct ancient pronunciations, historical glossing practices play a crucial role. However, although studied thoroughly by numerous scholars, most research has been carried out in a qualitative manner, and no attempt at providing integrated resources of historical glossing practices has been made so far. Here, we present a first step towards the integration of resources on historical glossing traditions in the history of Chinese. Our starting point are so-called fǎnqiè spellings in the Guǎngyùn, one of the early rhyme books in the history of Chinese, providing pronunciations for more than 20000 Chinese characters. By standardizing digital versions of the resource using tools from computational historical linguistics, we show that we can predict historical spellings with high precision and at the same time shed light on the precision of ancient glossing practices. Although a considerably small first step, our resource could be the starting point for an integrated, standardized collection that could ultimately shed new light on the history of Chinese.