Great idea! Even we should be able to prioritize certain regions or continents. Or start converting from earliest, or closest to your borders, or convert the provinces which won't bring the unrest to positive or to a user defined threshold like 5% or 10%. this would be a great addition but i don't think this would be implemented any time soon.
as a separate suggestion related to this is: on the conversion window, as an addition to conversion time, we can be given the current unrest number for the province and its region. I'd love to be able to go to the province when I click on it, too.