Guessing brake size

Got a message from a buddy about the brakes on his 67 barracuda with a 7 1/4 rear and factory v8 auto car

He hasn't pulled the wheels to measure them but ask what I thought.

Been a long time since I had car like his, but my 1st car was about the exact same as the one he is working on

I told him it would have 9" or 10" drums but without removing the wheel wouldn't know for sure.

So there are so many knowledgeable people here, what would you guess on a factory 7 1/4 rear end 9"? My 67 dart had 9" all the way around but it was a 6 cyl. Car