Ezeli's NGC waiver date is 6/30/17, so for that to be of value to NY, the trade would have to occur before that date, so only the 16-17 contract amounts matter. For this league year, NDour is 543K, so not enough to get close enough to Ezeli's salary. And yes, we have a trade exception, but it's only $400K, so there isn't a player out there that would fit inside that slot.
If using minimum salary guys, we could deal Ezeli+pick for OQuinn/NDour/Plumlee. Otherwise, Kuzminskas is really the only option (without using a third team). And of course, that's only if the Knicks value a first round pick more than O'Quinn himself.