"I have abandoned the idea for now, since I decided I really wanted movements and 1:1 magnification, so I'm trying to figure out bellows."

19" Artars, APO Raptars, Process Ektars, ect. are rated for 16"x20" at 1:1 so you really don't need a 24" lens, very likely get by with a 16" lens. Portrait lenses in the 20" - 24" range are all far too heavy for a foam-core camera. For bellows and movements just canibalize a 5x7 field camera and adapt to the front of yours.