Spacer between hub and rotor?

[GeoffP]

I need to space the rotor on my 87 IROC out by about 1/16" in order to properly center the rotor in the caliper bracket. There is no way to reposition the bracket inboard without re-machining the mounting point on the axle (which isn't something I have the sources to accomplish locally). I have looked at 1/16" wheel spacers. The problem with this is that the spacer HAS to fit up inside the rotor hat. I saw some "stock car" spacers on a site that I thought might work, but they are 5x5 instead of 5x4-3/4. Suggestions???