The incorrect buttons are in fact A body pieces, as you can tell from the shape . The B is more square and slightly textured at the very tip.
A body is more smooth, rounded edges . IF , and it's a very big IF , the above radio came from the assembly plant with those buttons, it would be because they ran out of the correct ones, and it would be the only one I have ever seen (and I have handled at least 175-200 1970 B body radios in this shop)
By the way, Their were 2 diffrent vendors for the 1970 B body radios
(Bendix and Phillips) 3 diffrent buttons for the 70 B , and all 3 buttons have the squares facing up .
I have seen a couple cases where some dork took his buttons off and tried to turn them over , but that's another story.

Greg