I use either the 120 Makro-Planar or the 180mm Sonnar. For tight head shots, either a Proxar or an extension ring is needed with the 180, but I prefer the more natural perspective that the extra camera-to-subject distance provided by the 180. The 150 Sonnar sits in the middle, and many like it. Note that all of these lenses are almost abusively sharp. Many subject will appreciate a little softening of their images - either with a Zeiss Softar or some other form of diffusion.

I believe that the all-chrome lenses were for the earlier 1000/2000 models. I'm not sure about full compatibility of those lenses with your 500C/M.