You need to check a few things. How does the model trim in the air? If it pulls to the right under high power, but to the left under low power, then you have too much right thrust. If the rudder is neutral in flight, and there's not much yaw when you change power, then the thrust line is correct.

Ground handling is not corrected by changing the thrust line. You have to work with the landing-gear geometry. When you push the model along the ground with the engine off, the model should track dead straight. The main wheels should have zbout one degree or so of toe-in. Toe-out will make ground handling a nightmare!

When set-up correctly, the model should need slight right rudder on takeoff to keep it straight. It may need none, depending upon how the thrust line works out.

The fact that you need right rudder on the landing rollout suggests that there's a problem with the landing gear geometry. You should need no rudder input as long as the model's tracking straight. Rudder input would be used to keep it straight. Holding rudder during rollout means that the wheels aren't aligned correctly.