I am not sure I agree that the blades are not period correct. I am sure they were available in the mid 70's, though I believe they were 'state of the art' at the time.
Yes, state of the art, but then available components did not really accept radial spokes, thus the questionable parctice of slotting of hub spoke holes to accept them. It's more of a customizing practice done by a very few and not what is seen on production bikes.
Chombi
84 Peugeot PSV