Yes, you can connect it directly to the rudder horn, but make sure to get the least amount of tailwheel travel that is possible. I'm serious, you do not want very much tailwheel travel. Look at the picture of your tailwheel wire. It is cantilevered way behind the pivot point. Any travel will be amplified. If (judging by the picture of your set-up) the rudder moves any at all, you are going to be over-driving the tailwheel. This is what makes the model so steering sensitive. Try this, Unhook the springs from the rudder horn. hook them together and to the tailwheel mount bracket, making the tailwheel straight ahead. Now try taxiing the plane. Does it still try to spin out? If not, then my point has been made. If it does still spin out, then you have an issue, either with the toe-in or the drag on the front (main) wheels. I would be willing to bet that it does not spin out as easily.

Be aware of one thing; Taildraggers are a ground loop waiting to happen. Be smooth on the rudder, and don't make big corrections. Small movements of the rudder are the order of the day. On a Cub, the rudder is very effective. So is the tailwheel.

On my WACO's, I normally limit the tailwheel travel to about 10 degrees left and right.

Bill, AMA 4720
WACO Brotherhood #1