I just completed a retrofit on an old Linde CM56 (now Esab I believe) trace cutting machine, What you need to look at is if your machine has considerable mass in both the X & Y axis, and if you want a fairly high traverse/feed rate, especially for small gauge plasma cutting. Then some form of reduction is neccessary, I used precision planetary gearbox by Bayside. With steppers I would never have had the speed, so servo's were used instead.
I used the Acroloop 4 axis motion card and Acrocut software, It is set up for Gas/Plasma/Punch marker.
Some of the major cutting table manufacturers have used this software (MG Sytems & Koike Aronson etc).