I also have the thick Willwood hats.
Look around to see who makes a steel hub. They should be much thinner.You will have to figure out the difference in rotor placement to fit the caliper and adjust, but maybe with some luck, a set of hubs, and maybe rotors, you can gain 3/8 to 1/2 inch. I was considering it if I redo my chassis for more tire.

8..603 156 mph best, 2905 lbs 549, indy 572-13, alky