One thing I can add on the shims that I've found through experience is if they are "missing", take a strong light and look down inside the steering tube often they have just slipped down inside. No need to get hung up on the shims if they are lost either. By my calculations you can use .033" shim stock, @FSH
had a good suggestion of using a layered material to achieve the desired thickness.
Thanks for offering this nice project Mark!