Hi Neil,
I find longer focal-length macros work better on small (35mm) cameras since they provide more working room. LF cameras already use long focal lengths so the focal length only affects the perspective.
True macro lenses are available for LF. They're optimized for close work, unlike normal lenses.
For critical applications you will probably notice a benefit to using a macro lens.
But for normal images, even closeups, a regular lens will work just as well.
As previously mentioned, a major problem may be the length of your bellows.
For a 1:1 (lifesize) image, the lens must extend forward of its infinity position by a distance equal to its focal length. Your bellows may not be long enough to accommodate that.
Example using a 300mm lens with 300mm FFL:
At infinity focus the lensboard is 300mm from the film. At 1:1 it's 600mm from the film.
- Leigh