Having tried to do what you are dong with both a crossbow and a vertical, I have to ask why not just do the easy thing and shoot an expandable?
To my satisfaction I proved that barely discernible differences in balance and on a spinner can easily translate to unacceptable variance in impact at only twenty yards. 4-6 inch variance was not at all hard to achieve with tiny imbalances or off center so small it was very hard to see. I didn't try a whole lot of different heads, but all of the expandables shot right with their "dummy" head. The best fixed blade head was the NAP Thunderhead as far as accuracy went. I did shoot a nice doe with the Thunderhead later that year and I hit the off side shoulder joint (tib/fib and humerus joint). It center punched the joint and severed it cleanly into three pretty equal sections. The arrow exited about 4 inches I suppose. The blades were slightly wavy but basically undamaged. The rest of the head showed no ill effects.
29 inch draw at 70 lbs is plenty to drive a 100 gran expandable through Bambi. Even with the large 4 blade heads. I firmly believe in two holes and prefer those holes as large as I can get them. After finding that fixed heads were likely as not to shoot to a different place after pulling them out of a target, I decided to take my chances with a possible malfunction of an expandable, something I have not personally seen happen either to me or the people I have shot with.
