I am at a loss to understand how you can change a boring machine into a MIG welder.
Do you mean this has a table with an overhead drilling platform that can move about the table and drill holes where you want.
You want to replace the drill with a MIG or Tig welding torch and use it to automatically weld to a pattern

The electronics look very old. Does it all work, or have you just got all the parts that you want to assemble.
This forum is for Mach 3, and is not a general engineering forum (although we have a lot of good engineers) so to advise you on that machine would be impossible, unless someone has experience with it.
Mach 3 is a computer program which runs on a P.C. It can provide outputs for up to 6 axis motors, to move them in accordance with a GCode program. The problem is the interface with the machine - your machine.
Mach 3 provides computer level signals (0 - +5V) to drive your axis motors, relays etc. It provides
step signals and
direction signals to tell the motors what to do. If your servo motors and amplifier system does not accept step and direction signals then Mach 3 cannot run it - and you would have to replace all your servo motors and drivers with ones that would.
I am sorry to be so gloomy, perhaps someone else to give an opinion