M_Boats: M15 mainsheet block?

My M15 is missing both the mainsheet, and the mainsheet hardware so I'm trying to figure out what to order. What brand/model swivel mainsheet block/cleat (the one which mounts next to the centerboard rope) do you guys recommend for the M15? Also, does anyone know the rope diameter and length for the factory mainsheet? Thanks, Tyler '81 M15 #157 "Defiant"