You're making a mistake on your arrow length! Trust me on this. If you draw 27.5" then your arrow should be cut 28" to B.O.P. (back of point). When you have arrow hanging off the front of your bow, you are affecting spine.
I was just in OZ bowhunting with a buddy and he was having arrow flight problems, big time. He had three inches of shaft too much. We cut three inches off and the arrows flew flawlessly.
I would recommend between 600-650 grains of total arrow weight. I have hunted Africa 15 times, so I have some experience. I recommend only one broadhead...the 135 grain, wide Magnus two blade. You will get a super blood trail with it and the heads are the finest I have ever used. The exception to this is animals like Cape Buffalo. For them, you want the narrower 125 grain Magnus.
I hope this helps...
Too Short