Crosley works at Hughes so I'm sure they make or market some different gearsets.
Kilgore is def an innovator in the TH400 world.
I like Chris at CKPerofrmance for his custom parts, although I haven't used any of the low gearsets for a 400 yet.
My understanding is that you use parts from the lower geared 700 or 4L60 planets to make the low (2.75) gearset for a TH350. You could also reverse this and make a shallower gearset for the 700, Chris makes a 2.66 first gear ratio for the 700 IIRC.
That would be a pretty good gearset in the 700.