hansgruber

I am looking to start a old world map project. Possibly a copy of the piri rese map or a custom treasure map. This will be on sheep skin (chamois), what kind of ink pen would be permanent and have a fine tip for crisp lines? Once done it will be weathered and damaged to give the illusion of old age. Newbie here, have done holster/sheath projects in the past with saddle leather. Sheep skin is a new territory for me and looking for tips. Thanks in advance!