The tormach controller is just a pc with pathpilot pre loaded that still has parallel port. Shred I think you are talking about the operator console, which is only available (to my knowledge) with M or above (no parallel port required). If the machine is running mach3 then that would probably make it a PCNC1100.
I will say as someone that started on mach3, I like pathpilot way better. I don't believe there is anything special about the PC from tormach other than it has usb3.0 and parallel port. If you can source a box (try newegg refurbished) that has a parallel port or room for a card I think you could go that way. Not sure if pathpilot installs as a linux distro or if you need to do that as well. You would need someone smarter to guide you there.