I love osage poles that size. I saw them in half, lengthwise then bind them back together with spacers between them for air circulation. Seal the ends and give them plenty of time to dry. I just remove the bark and use the sapwood under as the back. Seal the back after you remove the bark.
PA Magazine had an article years ago called "Limbows", by Dane Snodgrass about the limbows that Sonny Imans built. They were incredible bows.