I'm a bit confused why you would want two 150mm lenses, already having a 150mm Fujinon. I would pass on the single coated Symmar with Schneideritis for $150.
The aperture scale for the 210mm will not be correct, and will probably not be exactly correct for a 150mm tessar (Fuji) versus a 150mm plasmat (Symmar), although the scales may well be close enough.
The Fuji is likely a tessar design which will not have the coverage of the Symmar (listed image circle is 198mm for the Fuji and 210mm for the Schneider), although the Fuji should be fine for most 4x5 use. The Symmar likely has a larger usable image circle than Schneider lists, they were often very conservative. But I wouldn't pay $150 extra for a single coated Symmar over the Fuji; it would be far better IMO to put the money into a different focal length or at least a more modern, multicoated 150mm.
http://members.aol.com/subgallery/byfl.htm
http://www.schneideroptics.com/info/vintage_lens_data/large_format_lenses/
Steve