I don't think it matters much where in the lungs you hit them if you are slicing through both lungs, as far as deadliness. If both lungs are punctured they will collapse(not really fill up per say)and the deer will suffocate very quickly. However, very quickly can translate into 35 yards to 150 yards on the hoofdepending on the deer.

That is the main reason I tend to aim for the middle to front of the lungs and as low as possible depending on the angle of my shot, a low exit hole will work well even if the entry side is high. That way as the chest cavity fills with blood the deer is leaving a better blood trail on his/her "death run".

Here is a pic of a buck I killed with my blackpowder in 2006. The county I hunt allows rifles on the ground and I shot this guy out of a ground blind so the entry and exit wounds are on the same line. The shot "looks" good but that buck ran nearly 200 yards (not in a straight line) through the deepest, darkest, wettest, marshy pine thicket on earth(well maybe not on earth but it sure seemed like it that night). The blood trail was minimal and I literally had to go drop to drop to smudge to tracks through this thicket, on my hands and knees much of thetime, to find him. All in all it took over four hours to cover the zig zag trail no more than 150-200 yards(approx). Ever since that evening I have ben far more aware of how important it can be to hit them lower in the chest.

That is one exhausted hunter you are looking at in this pic, just glad I found him: