ok I dug a little, and should be pretty easy to do with off the shelf software, and a simple command line startup script.
You would run a VNC server to share the screen of the master Realvnc, or tightvnc. set for viewonly so that nobody downstream can hook up a keyboard and do bad stuff. On the slave (could do this with a pi or a pc) autostart the vnc viewer via a command line startup script with the ip and pw of the masterhard coded in. Simple restart of the slave will always seek out the master. All off the shelf and minimal effort to set up. could put in 10 dollar pi boards and re purpose the pc's forsomething more appropriate. Fixed ip address for the master for sure. I think the Pi also needs a fixed ip so that it doesnt fail by trying to start the vnc viewer before the address is obtained.