In general, I agree with the prior past, #13 is the "key" to the set.
Some years ago I purchased a lot of almost 1,000 of these cards from the family of a man who had owned a candy store. He opened many packs and stored the cards carefully. Many were like new, but off-center (I still have many of the cards if you are interested, practically pack-fresh).
I made multiple sets and ran short of the following card numbers to make another full set:
#10,12,13,26,28,32,37,40,49,55,60,63,64,70,73 and 74.
This is hardly a large enough sample to be conclusive, but I believe this list includes most of the "short prints" in this series.
I believe that the toughest cards are #13, #40, #49, #55, #70 and #74