Now that I've upgraded to a 4-piston Brembo brake kit on the front of my 1990 Z28, the brake rotor fits over the 2.75" OD hubs. Therefore, my 2.75" ID wheel spacers are no longer able to slip over hub and allow them to be hub-centric. Now, to have the spacers be hub-centric, I would need to have the spacers slip over the smaller/tapered part of the hub for them to take the load off of the studs.

The smaller part (outer-most part) of the hubs now measure 2-9/16" (65.09mm), while the inner-most part measures 2-11/16" (68.26mm)... about a 3mm difference.

What is my safest, most reasonable option to install 20mm wheel spacers? What have others done?

I will need at least .75" spacers for the calipers to fit.

Here are some from Summit Racing that are close, I think? https://www.summitracing.com/parts/stq-56050334