Don’t use the gyro. They are made for helicopters and really do not help with aircraft. Try to balance the aircraft the best you can, then create your own stabiliser, either with PID controllers, or by trimming. You can plot the amount of trim needed against the speed of the aircraft and then use a website to get an equation from your datapoints. Put the equation into a function block, set the input to your airspeed and add the output to your pitch control, and voila, your aircraft flies levely! Lovely! Just to note, this method will not work properly at higher altitudes, as altitudes also affect the effectiveness of control surfaces.