With that set up, and those big BH's, I'm first gonna remind you to ensure your bow is paper tuned perfectly. After that, I'm gonna recommend 5" feathers. With those BH's, yer gonna need the added stability. Blazers I don't think are gonna get that done. But possibly....What is your finished arrow weight?

And, to be honest, at the speed you are shooting, you just may never get them to fly good. Those heads aren't designed for fast shooting compounds....But again, try the feathers and see if that doesn't help.