Steepdiver

I know this is an old thread, but I need some help and it seems the most relevant. I am building a draw down stand and don't have the Stoleman books. My problem is with the top. I am having a hard time figuring out what is the best way to shape and Sze it. Any input would be helpful. Pictures would be awesome. I have saddles waiting for repair and a tree to start on. I just need to finish this first.