I've fitted a large Thornton Pickard roller blind shutter on the front of a large Darlot by using it without the lens hood. These too are uncommon in the largest sizes but have the advantage of a reasonable range of shutter speeds. I demonstrated this working combo to Eddie Gunks last summer. I have about a dozen of these shutters and they are very useful with shutter-less lenses. They were sold under the importers name in the US. TP shutters were made fror iver 70 years.

Thornton Pickard focal plane shutters are also available but again less common but they could easily be adapted to fit many LF cameras.

Ian