Here is the PDF of a related text that I am working with these days - Beal's abridged translation of the Abhiniskramana from Chinese.Romantic Legend of Sakya Buddha
I have been comparing the first chapter of the Chinese against Jones' translation of the Mahavastu, and the two texts appear to have been parallel versions of the same basic genre maintained by different vinaya-pitakas. The Mahavastu is a manuscript in unfortunate disrepair, as Jones points out. Comparing it to the Chinese, one can see where perhaps material was rearranged and newer materials (such as the ten bhumis) inserted. I'm attempting to make an initial translation of the first chapter of the Abhiniskramana as I go.