ref please
The closest you will get to a reference is FCTM normal ops, pre start: "The rudder pedals must then be adjusted to ensure the pilot can achieve both full rudder pedal displacement and full braking simultaneously on the same side."
This can be construed to suggest you should have heels on the pedals, as it is hard to achieve both full rudder and full braking simultaneously with the heels on the floor.
I believe this is an A vs B thing, different design philosophy, and I believe Linktrained hinted at that
