Idle Thrust : thank you, I stand corrected.
A few misconceptions here though:
but the airflow has the "twist" taken out of it by the airflow stab fins, but in doing so they are subject to side forces, if viewed from the back, they are twisted clockwise.
This results in a net twisting of the whole engine assembly.
Well, no. The twist was put into the gas flow by the engine, so taking it out simply retores the status quo ante. What you call "stab fins" generate a torque in roll, not a side force. And this results in zero overall net torque on the gas flow, and thus on the engine: straight flow in, and straight flow out.
We effectively have a captured gyro, moving forward, spining right, so preccession is left, causing the right wing to rise.
No, not so. Linear motion has no precessive effect, whatever its direction. Precession only occurs when there is a torque applied to the gyro in a plane in which the gyro's axis lies. No torque, no precession. In the case of an engine rotating about a longitudinal axis, a yawing torque will produce precession in roll, and vice versa. In this case, there is no roll or yaw torque applied to the gyroscopic mass.
Some older turbo-props had offset rudders to compensate (2 Degs for the 748/Andover) Not sure about newer ones.
Props - different case altogether. The engines apply a net torque in roll to the airframe (except in the case of aircraft with coaxial contraprops, such as the long-gone Gannets and Shackletons, and those with handed engine rotation - and then only in the balanced all-engines case).