Stepper torque determination

Hi everybody!

As a newcomer to home cnc machining I'd like to know
how to choose stepper motors.
The 2 machines I'd like to convert to cnc (a lathe and
a milling machine) are no desktop ones.
They are of the same category as the retrofitted milling machine at
http://www.bmumford.com/cncmill/. B Mumford says he
used 1400 oz/in of torque steppers. After I e-mailed
Pierre Rouzeau (http://otocoup.com/), it seems this is
an enormous torque for a stepper.
Even if the machine of the latter is a router and not a lathe, there
is a great diiference between the torque of his steppers ( 6.2kg/cm)
and those of b Mumford (1400 oz.in = 103 kg.cm).
How can I determine what torque would be best suited
for the machines I intend to convert so as to be as performant and
cost efficient as possible?
Thanks for help!!!!