'65 Formula S always have 10" inch drums on front or some had 9"?

Wrong. I have an early 65 Barracuda that came with 9 inch brakes, 273 4bbl and a 4 speed with sway bar. I also have the build sheet for the car that shows 9 inch brakes.
I'm looking in the master parts catalog (genuine MOPAR not a reprint) for 1965 and everything in there for 9 inch brakes indicated 6 cyl. Go figure . I don't doubt what you are saying but it has to be real rare . The V8 cars have heavier torsion bars , a heavier center link ,heavier leaf springs , you know they built them different than the 6 cylinder cars why would they stick in 9 inch brakes? it makes no sense .