I did a retro fit on a similar table over a year ago. The motors were actually tiny servos with gearbox reduction and top cutting speed was about 20 IPM. That works fine for flame cutting but is WAY to slow for palsma. Average plasma speeds are in the range of 80 to 180 IPM for 1/4 down to 10ga. on their table they did not want to cut plasma so the slow speeds were not the problem.
The machine you have is just not designed to have the speed or accuracy for plasma cutting. Keeping the tracing eye presents an even bigger challenge since it is part of the servo system. The eye generates an error signal if it deviates either side of the line and that corrects the tracking. Feeds an error amp that feeds a servo amp and runs the motors.
I bid the job for $4000 and lost my shirt. They too wanted to keep the "eye" and I spent most of my time trying to tie the two systems together. It was all custom work.
I would not recommend the exercise unless you are looking for a new hobby.