8 3/4 REAR - WHAT size brakes? 9" or 10-11"

Well, since the car was built over 47 years ago, that would be hard to prove. However, if you ask is it the same type as originally installed, well a peek at the build sheet would reveal that. What? you say, you got no stinking build sheet? After 47plus years, that's no surprise. lol. Well then, a look at the Fender tag will tell you.Oops, hold on, I thought it was in there. Lemme go check. Yup it's on the fender tag, but it will need to be decoded.
It's on the 2nd last line,under the "A",9th from the left.Grab the digit from there and report back. I'll see if my decoder will tell you what the car was born with. But it's then up to you to prove whether or not it's still under there. And if the wheel cylinders are the same size as original?who can say. I got no code for wheelcylinders.
So that more or less takes you back to square one. Sorry.....