With a 60 lb bow and a 27 in draw you are going to have to check out the KE you will be generating and get the best bang for the buck, or bull in this case. Luckily most elk are killed within 20 yards and a flat shooting bow is not a must, but good penetration is. I would find the combination that would give you the highest foot pounds of energy and then look at some good cut to the tip broadheads. Muzzies are great broadheads( I use them) but they will asorb a great deal of energy(if you have some to spare) penetrating into the hide. With your setup a cut to the tip would slice right through the hide and start doing it's job. I have used Modoc, Zwicky, and Phantoms in the past and killed elk with all of them. I would definatly go with a cut to the tip broadhead in your case. As far as arrows I would go heavier if you can. You should find that a heavier arrow will give you better penetration than the lighter one.