Plans For The 1840s Ballgown

I am in desperate need of a ballgown. I already have all the undies for about 1840-1870 and since I mildly dislike dancing in hoops and would rather not make myself six more petticoats, the 1840s it was!
I went to the library to look at some old copies of the Godey Lady' Book that they had and I found this wonderful dress:

I just so happen to have about 15 yards of  super wide lace from a planned bustle dress that never came to be so I knew immediately that this dress was the one. As far as color goes, I'm thinking a nice spring green like this one from Renaissance Fabrics:

Here's how the swatch looks with my lace over it:

I'm not the hugest fan of the ribbon decoration so I was hoping to replace them with roses, even though ribbon is more economical. I plan to debut the dress at the PEERS Twelfth Night Ball, and with all luck I can have the dress itself finished by Christmas.
Patterns for 1840s evening ware are extraordinarily hard to find. At a recent Gaskell Ball I received a tip from a lovely lady in an early 1840s dress that the 1830s pattern from Truly Victorian works very nicely with modified sleeves.