Many men in the Fluvanna Artillery were wearing recently-issued overcoats in February 1864.  Your best option for a versatile Confederate overcoat that you can use for this and many other impressions is to get a copy of the imported British army overcoat.  Among the first items of clothing imported into the Confederacy, and issued in some numbers through the end of the war, both East and West, there is no better all-around Reb overcoat option.  Made from some great blue-grey kersey, these coats aren't cheap, but they're the best reproductions of the original that have been made.
The overcoats will be made in two sizes, Regular (which will fit up to a size 42 chest) and Large (which will fit up to a size 48 chest).