I have made a few bows where I have ignored veritical grain and have been okay. These were all osage bows. I also had one break where the grain ran off. I would follow it if it was me. About the twist... If you only have an eight in difference then wow, just finish it and be happy. I always heat and try to remove twist, bit they don't have to be perfect. Perfect is better, but in my experience it is not necessary. I have gotten away with untwisting over at least 90 degrees of twist, but again, it was all osage. I wish I could help more, but I don't have as much acces to hickory. Good luck.