a few additions to
@reddesert 's advice:
• the standardization on compur 00, 0, 1, 3 is great and I have frequently moved lens cells from one shutter to another. There a a few gotcha's though.
- Copal made some shutters marked "Copal #3" that are sligly different and incompatible--called the Copal 3S. Sometimes the shutters are marked 3S sometimes just 3.
- I've heard of (never encountered myself) lens cells that flare out from the threaded area in such a way that they fit only certain era shutters.
- Compur 3 shutters don't open their aperture as wide as Copal 3 (I have a Apo Ronar 480mm ƒ11 in a Compur #3 shutter and transplanted in a Copal #3 it would become a 480 ƒ9.)
- most importantly, the aperture scales on the shutter are lens specific. If you remove a symmar 180, and replace it with a Fuji 180, they'll probably be pretty close to right, but if you replace it with a Fuji 250, it will be way off.
• there are a lot of LF shutters that don't follow the Compur 00, 0, 1, 3 convention--Ilex, Compound (I think), Supermatic, and others. These are mostly on older lenses or Kodak lenses, but they don't have quite the interchangability that Compur/Copal have.