I had a 900 head, and tinkered with the idea of installing it.
At the time, I opted not to do it. Not sure why I opted out.
Might have smaller valves?
I think I was a bit concerned that the C-10 piston dome might touch the head as the OD of the 900 chamber is smaller
than the OD on the ZG chamber.
MORE IMPORTANTLY: The 900 head does not have the upper engine mount holes that are on the ZG.
Or, probably I was just too lazy to follow thru with the project.
Ride safe, Ted