The XR5 420mm fits beautifully in the top. One might even think that the case was designed for a 420mm radiator in the top ... and wonder if there is a corresponding AIO. There is - the new H170 Capellix cooler and it will fit in there just like the XR5.
There's plenty of room for the fans to be configured as push pull. You have full clearance of everything on the motherboard. Not on the inset that you'll have the fans directly over the motherboard as well.
There are two limitations when using the 420mm radiator in the top. First, you won't be able to put a 480mm radiator in the side - the radiator covers part of the top mount. You also won't be able to put a 480mm radiator in the front. You could, however, put an XR7 360 in the front in push/pull with an XR5 360 in the side with a single layer of fans. That configuration is the most radiator that you'll be able to squeeze into the case.