That might be me. I have that lens on a Crown Graphic, but I don't use the rangefinder with it. The arm for the Kalart doesn't come out nearly as far as would be required. The front standard is pulled way out to near the end of the rails. For portraits, I need maximum extension and can get about 5 feet from my subject for a half length view, as in the example here. I used theground glass, and my subject had the chair to maintain distance, and I think I used f16. I think the Sironar is somewhat telecentric too, IIRC. Because it focuses at portrait distance does not guarantee your Nikkor 240mm will. If you tell me the flange to focal plane distance of your Nikkor when focused on a light bulb about 5 feet away, I can see if the Crown would permit that.
Crown Graphic with Sironar 240mm lens by
Howard Sandler, on Flickr
Nadine by
Howard Sandler, on Flickr