I really think most regulators 0-125 Psig 1/8FPT will work for you. You'll need to set up the new regulator with your old fittings and plug one port (plugs usually included). The main thing is to make sure the mounting threads are the same size where it mounts through the face panel. If you remove your old regulator you'll understand how it's mounted. The air pressure adjustment knob will need to come off to access the large mounting nut.
You won't use the gauge if included but will utilize this port for the gauge on the plasma unit. Most regulators have four ports, One for air in (unregulated) and two for gauges (one gets plugged) and the last port for regulated air. The two options for gauges are for configuration purposes depending on what side the supply side is on. Clear as MUD????
Take photos of your setup prior to disassembrly then study it and it will make complete sense to you. I really believe Hypertherm used a "off the shelf" simple regulator with a specification of 0-125 psig with 1/8" FPT threads. Also your post really didn't explain the "Broken regulator". Is it leaking or what? You should look at your "push fittings" to make sure that's not the problem. These fitting are very common and used in Pneudraulics applications. If I'm replacing these types of fitting I use Parker metal/brass fittings vs the cheaper plastic ones found in these units.