If you are not familiar with taking such shoots then I would not attempt it. The spine shot is a very difficult shot plus the target area is reduced by more than half ad to this the mass of heavy bone such as the shoulder blade and the spinal column and you can imagine how difficult such a shot is.
As it has been said here, the best shot is a slightly quartering away shot. But in the woods things are not allways perfect, actually they are never just perfect. That is the reason why I practice shooting all year long with the bow and the rifles. Once my weapons are sighted in I will never shoot at a range again. Instead I do all my practice under field conditions and I will practice every scenario I may encounter including the very difficult shots such as , steep down, steep up, with my body twisted backward from the hip up, around tree trunks, sitting, kneeling and what ever else there is. This type of practice gives me weapon proficiency and the confidence that I can take that difficult shot when it presents itself. But very often I still choose to let a deer walk for another day.