Lenses of that angle of view can be great for portraits, as can wides. A portrait does not by definition involve a tightly framed head shot or head and shoulders shot. A portrait is simply a picture about a person. (And I would personally argue that if it isn't about the person, but is simply about what they look like, then it is not a portrait either; it is "glamor," but that is a topic for another thread.)
So, while you may want a longer lens for the work you have in mind, don't discount the 150! The idea that all successful portraits "are" tightly framed and free of background elements could not be farther from the truth IMO.
If you want to have a press camera with the option of using a variety of lenses with the rangefinder, try selling the Crown and investing an a Super Graphic or Super Speed Graphic. They are the poor man's Linhof III, and are truly great cameras, especially when you consider how little they cost. Pacemakers and the like are not designed such that constantly changing lenses and also maintaining rangefinder use is practical.