Hi, having worked on many of these old machines in the past a word of warning. Most of these would not go any faster than 3M/min and we primarily designed and built for gas cutting only. We had retrofitted some of them for plasma cutting but the top speed remained the same. This cantilever type machine only has a drive system on the middle rail and uses the outside rail and bearings as a sort of counterbalance. The problem with this machine moving too fast is that it will whip on the outer end of the cross beam. Acceleration should be slow and smooth to prevent this. As you say these machines are quite heavy but were driven by small motors. The picture is not too clear but does it have gearboxes fitted to it?
What are you thinking of converting the machine to do?

Ian