Too many times we attribute poor ground handling with the tailwheel.First of all I would like to know how well your plane tracks on roll out and takeoff. I would suspect you have the same problem. If so the common problem is due to torque. Overpowering a plane with more engine than it needs, which means that the large prop is more that it needs, thus giving the plane too much torque and poor ground handling. just my thoughts, jmpups