We'll need at least 6.5 inches of width for each side, then add the width of the fingerboard at the 24th fret. Our regular 4-string width on an Essence is 2.36 inches, so the board must be at least 15.5 inches wide (since most lumber is rough on at least one edge). After sanding, we like at least .25 thick for the top. Most lumber you'll find for exotics is sold as 4/4 (about one inch thick)
If the board is thick enough, we can make the peghead veneers out of the same piece.