Now that he’s finally going to Washington after years of trying, Republican Tom Kean Jr. now faces a really tough choice that will determine what kind of a congressman will he will be. Kean can become a loyal Republican, following his GOP leaders and towing the party line — a path that could find him slowly rising in the ranks and gaining power in a town that values loyalty. Right from the start, Kean will face pressure to vote with his party as House Republicans at best can expect a very narrow majority and can’t afford defections if they want to pass anything. On the other hand, he can be th…