Wagons have different rear seats then the other body styles. You would have to take your rear seat out and have it reupholstered, or find another 63-66 a-body wagon with a nicer seat.
Ive used the two piece carpet kits before. Make sure after you unbox it, that you leave the carpet in the sun for a while to make it softer and easier to mess with. Other then that, just trim it to fit and it turns out pretty nice usually.