I used my absolute favorite pattern, Jennie Chancey's Regency Gown Pattern. I modified it a bit to make it look more like Jane's gown.
Here is a close up of the back. I used some of my great grandmother's shell buttons for the back.
A Full view:
A close up of the front:
I added some fullness to the front and also took a tiny bit of fullness out of the sleeve.
The gown is made from muslin. After researching the Regency era I learned that muslin was the most popular fabric for gowns. How often you wore muslin gowns, however, showed how rich you were as they were hard to keep clean!
I sewed the gown completely by hand.