Well, you're comparing bodystyle/engine/tranny and adding a vinyl top? Not quite an apples to apples comparison.

Anyway, here's a quick view of some of the rarest in the White Book:

1968 Sport Fury ragtop "regular" 440: 2
Same with 383-2 and 3-speed: 4

1968 Fury III with 383-2 and 3-speed: 4

1968 Fury II 2-door sedan 440HP: 3
Same with 383-4 and 4-speed: 4
Same with 383-2 and 3-speed: 3

1968 Fury I with 383-4 and 4-speed: 3