Once upon a time, long, long ago (Feb 2016) one brave soul took up the task of preparing J. J. Jone’s English translation of the Mahavastu for SuttaCentral. He performed magnificently in his quest, conquering a substantial part of the job, but due to other commitments he has to hand it on to someone else.
If you’re interested in volunteering to complete this preparation work there’s a lot of info about what’s involved (not to mention useful materials/tools and just plain fascinating stuff to know) in the original thread: Proofreading the Mahavastu. Also Stu (the chap who first took up the work) is happy to offer some guidance for the task to anyone who wants to take it on.
Drop me a line if you have any questions or might fancy it.