Here is a working, hard to find 80 column display card from Newell Industries called the Ramrod.
Paper manual and installation instructions included.
This card replaces the OS card with a OS B, The fast math ROM, and your choice of Omniview, omnimon, or 4KB SRAM in the address space of c000-cffff.
Incliudes the Omniview 80 column display rom add on. Toggles on in basic or DOS by jumping to address C000 or calling x=usr(49152).
You can also swap that rom chip for the Omnimon for assembler/testing/cracking.
Included is 2 2KB SRAMs it you want to use that 4KB space for programs.
The display looks best using a monitor that uses separate luma and chroma and plug in only the luma.
Manual and documentation on archive.org