Sounds really cool! BTW do you think it would fly with a 64mm if scaled up? (I am hoping to get my own 3D printer this fall...)
The new version will be designed around a 64mm fan right from the beginning. It's just a nicer size of fan to work with and with how much I like the Saab 105 with the extra power from the 70mm fan, I have the Powerfun 64mm fan I was originally going to use in that sitting around again.
For the speed plane version (50 mm), if you want to try and put a 64mm fan in it and fly it, I don't really see any issues with scaling it up, though that comes with the caveat that it was a handful even as the original 50mm plane. The only issue might be the elevon torque tubes which use 3mm carbon fiber rods, which would need to be 3.84mm carbon fiber rods in a 64mm scaled version. Nothing insurmountable, though.