Nice show.
Here is a Cups ppd for the DEC LN03
https://www.openprinting.org/printer/DEC/DEC-LN03
Here is the manual for it https://vt100.net/docs/0ln03-ug/ 
All you need is a usb to serial adapter. Looking forward to hearing about getting it running and putting that on the pi with the other printer.
Cheers
Turtle

