The HAMB tread list some information on this from a Ford Engineering Training Manuel that at least sounds factual.
Per Bruce Lancaster on the HAMB: To quote the Ford engineering text,
"The principal object of this [Desaxe] offset is to diminish the obliquity of the connecting rod during the power stroke, so that the mean thrust of the piston on the cylinder walls during this stroke when the bearing loads are greatest, is reduced."
http://www.jalopyjournal.com/forum/t...#post-10750147