Best guess: I'm not at my car and maybe someone else will chime in, but I believe that if it is to factory specs ( Well made repro or factory wing, not a Ford wing or such.), the spread between pedestals should be the same for the '70 and '71 Go Wings.
Best way to check, if memory serves me right is to look under the trunk lid and you'll actually be able to see holes in the under trunk lid support metal. Hold the pedestals (with the wing attached) up to the holes to see if they line up.