Thanks for the advice!
Found the following links that hopefully will be helpful to everyone:
Elk Anatomy Overview: http://www.bowhunting.net/NAspecies/elk2.html
In looking at an elk's circulatory system and bone structure, there appears to be two good spots to shoot for:
1. Heart and Lung area slightly behind the front leg / near the top of the shoulder.
2. Spine / Base of Neck Area. Following the forward portion of the front leg 1/2 to 2/3'rds up to where the neck meets the spine. There are a lot of major support bones in this area that when broken, should anchor the animal very quickly.