Noting your reference to M.F. Benton's Wedding Text I gather that your reference to "blackletter" means typeface in the style of Old English, textura, fraktur, etc rather than any dark letter, such as a very thick sans. You have some good choices in this category.
The best assortment of such fonts from the American Civil War era -- taken broadly as the 1850s to 1870s-- is by Michael Hagemann at FontMesa.
The one I like best as a textura is Black Pearl http://www.myfonts.com/fonts/fontmesa/black-pearl/ a revival of an 1868 design by West for the Farmer Foundry. You can simplify it by not including the swirls and it could look really effective when carved. In my opinion it looks like vigorous version of the design ideas found in Friedrich Bauer's Fette Gotisch of 1875 http://www.myfonts.com/fonts/linotype/fette-gotisch/.
Another good choice is Black Rose http://www.myfonts.com/fonts/fontmesa/black-rose/ a revival of the Bruce Type Foundry font called “Black Ornamented” created in 1873. A few years after the American Civil War, but I believe it really catches the spirit of the era.
Yet another with really good potential for carving once the ornamentation is discarded is Silverland a revival of a Bruce Type Foundry numbered font created in 1874, with an added lower case. Again, a few years after the American Civil War, but it too catches the spirit of the era. The basic letterforms are well proportioned and would work well in an inscription.
More from Michael Hagemann at FontMesa http://www.myfonts.com/foundry/FontMesa/ also http://www.identifont.com/find?name=Michael+Hagemann&q=Go
Don

This typeface was initially released in 1832, and would still have been in use during the Civil War...

http://www.myfonts.com/fonts/nicksfonts/boston-blackie-nf/

You might also want to visit the Walden Type Foundry. www.waldentype.com

Hi Nick, thanks for mentioning your Boston Blackie. This got me thinking about very dark & wide blackletters and I remembered Caslon Black, which was definitely in use during the Civil War. There is a digital version, as Avebury Black by Jim Parkinson, modified to some extent based by a Bruce version http://www.myfonts.com/fonts/parkinson/avebury/ Either font would work well in a carved inscription and would give it a very solid character.
Don

Everyone's comments are greatly appreciated!

I'll have to do some figuring on the heft of the text to ensure there is enough thickness of work to support it. Light (actually darkness) gives the carved letters dimension. To create the darkness, carvings are often done with about a 60 degree cut angle. The wider the lettering, the deeper the cut in the work. For this reason I may have to lean toward some of the lighter text weights suggested.

Again, everyone's freely offered help and expertise is truly appreciated. Now to choosing...