I have found turbine alignment, when using a thrust tube as we are discussing here, to be very non-critical. Sure, if you are a few degrees off you will be heating up one side of the thrust tube a bit more, but if your tube is plenty thick (0.008" ), no matter. If it is at least three diameters long, you won't notice any thrust misalignment. If you visually center the tail end and the angle with the tube, all will be just fine.