The shims should be steel. I cut them on a lathe out of solid bar because I didn't have any tube that size. You can probably find the right size tube then slice it off. I don't remember the exact size but it's close to a standard like 5/8 id x 7/8 od.
It'll be hard to tell if the bearings are bad with the car setting on the ground. I saw looseness in mine when I had it jacked off the ground, grabbed the wheels, and tipped them inboard-outboard. The looseness in mine ended up being at the threaded parts.