Im sorry but the artist that has both the talent and the time for this project does not exists if you want them to you are going to have to paid or else no one in there right mind will be up for the task. A year+ worth of work on a project with no pay and you want two artist good luck but that is just not realistic.
But to have a better chance you would want to post a portfolio of games that you have made in the past and any thing that you have created.