If those are what I think they are DC brushed motors and can be simply run with an automotive battery to see if they run, it would pay to check the brushes (length) and inspect the commutator for wear, but they are fairly beefy motors, the size usually fitted to Knee mills etc.
If you use them at the max voltage you can up to the rated voltage you may not get full torque, but maybe enough for a gantry, especially with gearing.
You do not need the tach with modern drives so just remove the tach brushes when used.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.