Building Plasma table 1250 x 700

How much travel for one revolution of the pinion ?
You need from 15 to 25 mm of travel per motor revolution.
Nema 34 are to big for that small of a machine, even some 1.2A nema 17 will do just fine. Big motors cause big vibrations, so you will need microstepping to avoid vibrations, at least x8.
For Z axis you need at least 400mm/min, 900 to 1200 is plenty fast, with your motor and voltage very easy to achieve with direct drive.
As litle as possible, just enough to trip the switch.
Make the Z axis longer so you can have the water table at least 15 cm below the machine frame, keeps the water from getting all over the machine. 10cm travel is a bare minimum for comfortable use, 20 would be nice. This is for Z axis travel.

You can try direct drive on the X and Y axis, if you have drives with good microstepping and can afford to go x16 or x32, might get nice smooth motion despite the long travel per revolution.
Had to do that on a 3.5X2 m machine using direct drive and nema 34.
Been nearly 4 years from that, almost forgot to mention.