Well, I don't about the sound if you use it for the top, or back, it might very bright, or very dead. Sitka Spruce is still king, and some guitar makers like "Lund" are using Cedar. I would think that Osage would make a nice laminated neck, or a one piece neck, or even a fret board, and bridge, as it will darken over time. I think you are putting yourself in for some hard work, and frustration. Like they said, a 24 inch Osage board, will be like trying to finding an original Gibson D28 banjo, with the checker board perfeling, or however you spell it, and the gold flake finish, in mint condition, at a yard sale. Better to look for 12 inch wide, and go with re sawing, and sanding. But even a 12 inch wide Osage is not readily available. It will take some looking, as I am sure it is out there, it's just a question of where. I don't know if it would even make a good sound board/neck attachment block. But it does sound interesting. I know a guy down here, who did some repairs on my Martin, and he used to work for Ovation, and now is a warranted repair site for Martin, and other companies. Well he made a beautiful acoustic guitar out of some Hawaiian exotic wood, but it was very heavy. You would need a strap for sure. Good luck, and let us know how you progress. I too would like to eventually make a guitar, as I have some ideas, I would like to try.
Wayne