Mmm Having flown Colin's DerJet Cougar a fair bit, I think although a yaw (rudder) gyro will help, it needs an aileron gyro! When flying slowly in a breeze it wags its wing...
But there is no down side to fitting a rudder gyro first and seeing if it does what you want. ACT gyros are not cheap, they also are not made in anything like the quanties as helicopter tail gyros...

Dave