Well they don't make Dagors in anymore and they do render beautiful smooth images. I'd keep it. I have a 7 inch Dagor dating from the teens, it is beat up but got me hooked on Dagors. It was remounted in a Copal #1 shutter. The 6 inch Dagor I have came in a Compur #0 shutter. so that may be what you can look for, an older Compur or Copal #0 shutter to replace the Ibsor shutter. Or try Flutot's Camera Repair or Paul Ebel Lens Service to revive the vintage shutter.
That said, Dan's suggestion of a modern lens and shutter is a lot less trouble for everyday shooting. Keep the vintage lens for a different look.