Jay,
Since you already have what you have, I suggest you go with it as is. As I said in my other post, torque is not the problem with your power supply. You WILL get the rated torque if you can provide the required amperage. The issue will be how fast you can move. Voltage relates to SPEED. I'll bet you can get things running with what you have. If you later determine that you want higher speeds then a different power supply would be in order. Many find that they don't need high rapid speeds, especially if it is a small machine.
Using the maximum the drives will allow will get you the maximum performance available, but you may not actually need it.
4-wire steppers don't have the choice of parallel or series. This only means there is one choice instead of two when you look up the specs.
The motor label saying 24 vdc is there because the manufacturer says that voltage with the max current will not overheat the motor. Running higher voltage means you need to keep an eye on motor heating. My CNC mill uses Compumotor drives at 170 volts. Marris (Mr. Gecko drives) wrote a "White Paper" that does a very good job of explaining how you can make sure your motors are treated nicely. I suggest you download a copy. It shouldn't be hard to find.
