Very nice, ive completed a rebellion before, was pretty tough, what i did was, before starting the rebellion i did about 3 tasks for each lord to get on their good side, i then started the rebellion and converted like 5-6 lords straight away because of my relation with them, took a small castle, gave it to one of the lords and then took the surrounding cities, didnt take the capital for awhile though.
EDIT: What i want to know is what happens when you win and you havent converted all the lords? Do they disappear, and so your new kingdom has fewer lords than the rest because to my knowledge new lords dont appear.