I don't know about a 7' swinging around. Might not.
I use an 8' back blade on my 3000 but the blade can be shifted to one side so I can still turn it around.
8' is just right otherwise.
Not sure about the 9/2/8Ns and Jubilees.
I do know that Ford changed the geometry of the 3 point linkage when they started the Hundred series. Not the same as the Ns and NAAs. Pretty sure the lift arms are longer on the later models.