Hey Ted - thanks for digging out the numbers. You've definitely shown that it's likely they were 350 only cards, but I've got one more question
Can you confirm that none of the the PB cards that we know are 350/460 cards showed up only 5 times in your sampling? If they all showed up at least 6 times and the O'Hara and Demitt showed up only 5 then I think you've proven it as best as you can statistically, but if some/several of the 350/460 PB cards appeared 5 times then the O'Hara and Demitt showing 5 times doesn't prove they are 350 only cards.
(BTW; it's not that I believe it to be a 350/460 card, just that I haven't yet seen conclusive proof it's a 350 only)