Belts and Pulleys

Hi All,

I'm in the process of CNC'ing a ZX7045 mill and just needing a little
help in working out the pulleys to use for the Z axis.

Have changed to 3/4" .2 ball screws on all axis.

Driving X and Y using servos with a 3:1 ratio.

Have a 1200 oz/in stepper for the Z axis.

What would be a suitable ratio and pulleys "L XL HTD GT2" to use on the
Z axis?

Thanks, Rob