No fuselage stretch. The firewall forward weight with mounts and everything was about the same as the original 582 setup. The CG is perfect. I can pickup a 912 by myself. Very light engine. The 582 setup had a lot of steel for the mark Iv mount.
I would love to see pictures of a design where 2/3 of flaperon works as flap so it could be pulled down 30 degrees or more and the leftover 1/3 work as aileron. I think it would greatly improve landing capabilities. Might lose some aileron authority but with rudder would be okay.