Is the conflict in One Thousand Dollars, by O'Henry, person vs self? Gillian struggles to spend his money and with doing something decent?
I would agree that the conflict in this story is that of a person versus himself. I would put it just a bit differently than you do, though.
I do not think that Gillian is struggling to do something decent. I think that the struggle is to figure out who he is. He is not trying to move in one direction -- instead, he is trying to figure out which direction is right for him.
I think that that is why he goes around asking people for their advice on how to spend the money. I think he is trying to decide if he is the kind of person who buys necklaces for showgirls or, perhaps, if he is the kind who banks over $1000 by selling pencils.
I think Gillian struggles against himself to find out who he is.