2 300oz+ servos will be fine for rudder..... most planes are designed to have them under the hatch pull pull style... however if you are using a bigger engine than recommeded or a really heavy engine, push pull might be the right thing to do to help in balancing

what size plane is this? hopefully 50cc that's the perfect size to start off with to begin the giant scale journey..... you might want to get a hold of some locals to guide you in the right direction