JC:
I wrote the fuel-management article which you can access from
www.SkymasterUS.com, but it's for a normally aspirated 337. My quick analysis of the figure you posted suggests that indeed you can draw fuel from the auxiliary tanks after you run the mains dry in a Turbo model. That's because the auxiliary fuel pump is AFTER the fuel selector switch, so it pulls fuel from whichever tank you've selected. In the normally aspirated models, however, notice in your figure that the aux pump only draws from the main tank. And, as you know, you've got to have the aux pump if there are voids in the line (which, as you know from my article, will occur if you drain one tank dry).
Ernie