Finney gave the WSJ a bunch of private emails between him and Satoshi from 2009, linked below. I suppose it's theoretically possible Finney spent a lot of time faking this convincing set of emails, but absent that possibility, I think this seals the case that Satoshi was not Finney.
http://online.wsj.com/public/resources/documents/finneynakam...
As an example: https://en.m.wikipedia.org/wiki/Dialogue_Concerning_the_Two_...