BlackedOutREVO, a Neu finned will fit fine, you just might have to remove the rear motor support. My motor is not even resting on the rear support, it is just a few millimeters above it. I think the support is only there to help in extreme violent bouncing situations.
David, my Flightpower 6S packs fit fine in the frame. The frame itself is very, very rigid! I was suprised at how rigid it is for its length. It is 6061-T6 and almost 5mm thick. The whole kit is very well made and includes some surprising extras. Like a micro servo mount with appropriate frame holes, so that you can use the reverse module if you want! Bargain for $185.