Something seems strange about this.

What spindles do you have?

Do you have a picture of the interference?

A picture of the uca installed on your car?

You said you drove 100 ft with the 4.93" back spacing and there was some minor scraping. Did you have spacers on those when that happened?

Where exactly on the rim did it scrape? Where on the UCA?

So the 4.5" was the exact same? With spacers?