UCA Bushings don't fit?

Will Gant said
…….. My understanding was that factory v8s got the 10 inch and slants got the 9 inch.

FWIW, Here's the 9" drum set that came off my '69 383 S Barracuda. I swapped in standard '74 Dart disc in the late '80s. I don't think anyone would swap 9" drums in over 10". It had 14" SBC Cragars (now rotting in the shed I think) on it and their wonderful lugs that liked to loosen up, but never had a spindle issue. It did tend to eat up drums. The sway bar was gone long before I got it.
Here's what came off...….