Graupner/JR DS5391 is a good and sheep servo. You can have it on Ailerons and Elevator. Infinity 90 is a light plane, I would have DS5391 even at the rudder.

NOTE! You are not allowed to have 5 NiCA cells or 5 NiMh cells at the receiver battery together with Graupner/JR DS5391.

At the throttle Hitec 225 BB is a good choice.