Shawn,
What material is it? If it's cast iron, then a straight flute tap would be okay, maybe a plug version instead of bottoming, though.
What kind of machine? Does it do repeat rigid tapping?
I would think that it would be good to take a couple of passes to do the hole, so that you could get some new lube on the tap as it progresses farther down.
Have you considered thread milling? This is what I would recommend for the cleanest looking threads, and far less brute force is required to drive a thread mill than a tap.
If its a blind hole, a spiral flute is generally the correct choice for normal tapping.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)