does the engine look straight, rather than taking a measure of what the steering is doing ? is the outboard offset mounted, as it should be ? Does she have power steering that perhaps needs bled ? There will be a natural tendency for a RH prop to force things to starboard. Very noticeable with cable steering, but the power steering should be able to keep her from the prop throwing the actual engine angle starboard.
I am sure you will also be aware that often, this sort of thing can be evident when you have the wind influencing things too. So if you have a wind blowing on your port side for example, to keep the boat in a straight line you will naturally find yourself steering to port to keep the boat running straight, but can mean that you experience a heel to port too. This is especially a behaviour noticed when running on plane at cruising speed, with very little hull in the water to counter the affect the wind can have on a boat with a fairly high air draft. The affect is lessened somewhat with more pace and/or a little trimming out on the engine (if applicable)
