There had been many discussions about it with plenty of historical evidence and clever thoughts.
Basically, my guess, while I agree on the stronger weld is: The 427 owners wanted to use the same quick jack as they used when they had a 289. This is how you get your spacing.
Facing forward or backwards is the result of the clearance of the jack at the
oil cooler opening of the 427. Or you made a new jack to clear. Now you can also space them as you like.
To engage the jack seems to be easier when the long ends are close to the body - definitely facing down ;-)
As for fronts stronger than rears in spite of 50/50 weight distribution, I don't know. Also, you could probably lift up a medium size cruise liner with them.
I do know that the radiator frame gets bent quite a bit lifting the car which elongates the holes in the aluminium skin.
Nice debate, but a bit overrated? :-)