Couple of questions: first of all, which case do you have in mind here? I can see a tile row, but is this an Intellijel cab or a 'standard format tile' 4U 84hp case? Second, if it's not an Intellijel, did you have a powered option in mind, or unpowered?
Last: do you think this size is actually sufficient due to portability constraints, etc? The Phonogene and Maths eat a lot of space, and even though this is just a processor cab, you might find that going to two 3U rows makes more sense in the long run.