Ok , I reran the numbers through OT2 and using the same arrows your have at 28 inches long, Is that how long your arrows are, and using the 125 grain heads , if you went down to 67 lbs you would be in the middle of the green . 66 lbs put you slightly on the heavy spine side but for broadheads would be fine. Most people dont want to drop their draw weight for fear of losing too much speed.