There are precision angular shims that are commercially available. They come in
1/2, 1, 2 and, 3 degree angles, if I remember correctly. More than one shim can be stacked if larger angles are required. They greatly simplify the process of adjusting the thrust line. A little 3M75 repositionable contact adhesive will hold them in place while the mounting bolts are being screwed down tight. They are easiest to apply with radial mounts.