Oops, I commented on window parts too not having seen the previous reference.
I looked at the knobsknockers site (hmmm...disappointing, no actually, nice stuff!)
I bould a similar straight version of the 704PB at a local hardware store. I could not envision what purpose the curved (as in 704PB) one woul serve for a view camera, unless you wanted rise and tilt without being able to control them individually!
I avoided the ones with the fixed incremental stops and chose a fully slotted frictional clamping one.