Custom lettering is not always based on an existing font. You might dig FF Tartine Script.

This is kinda, sorta like it...

Letterhead Fonts also has 'Ballpark Script', which even comes with a set of swooping swashes for the underlining part, but be aware, you need graphic software to attach them to the words. They also have a more antique style, called 'Ephemera', also with the swashes.

- Mike Yanega

excelent font