I have a Beslon 100mm f:4.5 enlarging lens marked Beseler Wetzlar that I've use with excellent results on a 39mm bellows with chimney finder and rangefinder bodies. It's also done a fine job as an enlarging lens. Most likely it's a double Gauss design. The aperture is about 16 blades and stays very round. Bokeh is great and I like the working distance with the longer focal length.

I've also use the head from a 135mm f:4.5 Steinheil on the same bellows with great results at macro distances, but it's not 39mm and needs an adapter that came with the bellows.

My 40mm Apo-Componon HM also works well in this setup, but with the bellows the minimum magnification is greater than I normally use for macro work. It has a sort of "pincushion pentagon" aperture, and I haven't shot it enough to get a sense of the bokeh with specular highlights.