Looking at your setup, you are shooting quite a heavy arrow, and the speed shouldnt be all that fast. With that being said, you should be able to get good broadhead flight, with a fixed head, if the bow is tuned good. Why the need for the mechanical? or are you just looking for a larger cutting diameter? Best of luck with whatever you choose, but if I was shooting that set up, I would probably go back to my slick tricks.

Jason