I see that its cast iron, so see if your fabricator has a TIG welder. If so, good, as TIG welding of cast iron is the way to go its fast and reliable.
All you do is knock the flux off some cast iron arc welding rods and use them as filler for the TIG. As for gas the standard argon gas used for stainless will do fine. You can get awya with little of no pre-heat of the banjo
I have done this on my own cast toolrest a couple of times and for others around my neck of the woods, never had problem with any of the joints