Are these motors Servos? If so you will  need the rated  voltage if you want to get the rated  speed and same for the current, if you want the torque you will need the current.
Hood

hood,

They are nema 42 steppers.

fastest,

That is what I meant.  Little mistake.  I am having trouble getting 8amps per motor, but it seems like that is a max, and I could get away with less.  Some poeple are even saying that I should go less to make the motors smoother.  I'm not sure on this stuff.  Anyway I will get it worked out. 

Sorry for the confusion.

For speed think high voltage

For torque think amps

I would go for high voltage, as next you will be complaining that the machine is too slow.

Well normally steppers have low voltage, usually about 5v. Are these old motors?
Not an expert on steppers, or anything else for that matter but normally you go 5 to 20 times the voltage of the stepper with the modern type drives.
The same holds true I think in that voltage will give you speed and current torque but on steppers especially too high a current will give lots of heat.
What are the motors off? are they the sigmas off a Bridgeport? What drives are you to be using?

Hood

Hood,

They are off of a piece of packaging machinery.  They are Pacific Scientific powerpac motors.  The plate says 65dc @ 7.9amps  300w.  I'm not sure if that is a max or what, but it's going to be hard to get that kind of power in a household environment.  They are Nema 42 with 2 stacks. ( i guess that's how you say it)   I have no idea what the stacks mean.

Almost forgot.  They are driven with three pacific scientific 5410-010 drivers which i haven't managed to get the connection schematics for yet.

To get the speed you will need to get the 65V , or as close as you can, I would say.

Hood