ooo... i see. you actually don't need to change anything except adding the Y-servo extension. the servos are already in the right position so that you don't need any kind of reverser. just connect and everything should be working correctly.

while the Y-pushrod is a great suggestion, i'd be a little hesitant to try it if i were a beginner since you have to tear apart what's already there and fabricate a Y-pushrod, while not difficult, as a new builder, i would stay away from that.