Hi Carl,
I agree with Mike that the top of the FAB is known to be a crack location (although many have gone to a simple brace attached to the carb bolt that seems to be helping a lot!), and I would be nervous about a rigid fuel line between two "masses" (even a light one like the cube) in an area with vibration.
If you're looking for simple and compact, I have had great luck so far in the -3 with the red cube on a bracket from the front sump bolts, and custom fuel lines to connect it up. The red cube is between the servo and spider, and is incredibly accurate.
Paul