I suspect that you would find way better correlation with previous positions of leadership and being a successful President. That leadership may have been political, or military, of even corporate. Anybody who has successfully run a large organization (without excessive sociopathology) might make a good President.
The people to ask would their employees, their chain of command, and their victims, to see if they passed the "ethical human being" test. In other words, he or she has to be a "mensch".
