Feed Rates

I'm trying to spec out what motors and power supply I am going to need to convert a Sieg X3 to CNC.

For the purpose of sizing the motors, what feed rate should I use for cutting and rapids?

I will be cutting aluminum 90% of the time.

Any recomendations on torque would be appreciated. I' thinking 640oz on the X/X and 1200oz on the Z ?

Thanks
John