@Psylence: I can't claim credit for the parchment; it's a scan of an actual piece of paper. All I did was set it on its own layer and set to 'Multiply'. Presto.

@Max: I'm kind of leaning that way too. I'm leaving the right and left sides open for some other stuff, and I want to keep the longer horizontal aspect of the whole piece, so I think I'll experiment with placing the title box inside the map and see how it looks...