These are the last two that I'm going to look at, giving me 6 cults, 6 unique explorations of pint finish. I then have to figure out how to maybe expand the brief out a little bit.
http://listverse.com/2007/09/15/top-10-cults/ has quite a long section on them that would be suitable for body copy. Key things to latch onto; their name 'solar temple' conjours up imagery of really vivid yellows and interesting sun-like shapes. I also find that the most shocking/interesting thing about the cult is that they got one of the families to kill their own child, believing him to be the anti-christ.
http://coolopolis.blogspot.com/2007/08/order-of-solar-temple-coolopolis.html This website has a personal interview with someone who was quite close to the cult. It's quite informative and will fulfill the requirements for the vertical strip of text quite nicely.
Finding an image of a suitable size, even when half toning has been difficult. The cult was quite secretive and their aren't many images available, however, this photo of co-founder Luc Jouret should probably work quite nicely, given that I can scale it up when turning it into a halftone screen.
I think that's all I need, I'm aware that I need to increase the rate at which I'm producing this work a little, so in terms of research I need to move quite quickly.