Got it,
I was working with old GM rims, they're quite thick where the clips were riveted in, plenty of meat for a 10-32 screw.

I bet you could get by with two screws holding on your adapter block if there's room, 0.100" is likely enough meat in that case.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-