Best bet would be to get rid of the 3 in 1. But to do that you'll also need a tail motor ESC. And yes you will need a HH gyro. I'm using a cheap $40 Telebee gyro which works perfect but all my stuff is still brushed but the telebee should still work fine in your app.
http://www.helidirect.com/telebeezoo...sion-p-494.hdx