After at least four iterations, I’m getting pretty slick at drawing brake brackets, levers and rods. Along the way, I’ve reviewed countless drawings for brake gear and learned so much about the KC brake system, some other memories must have had to pop out the other side. I’ve finally arrived at a version with which I’m comfortable. Or at least, I’m so tired of monkeying with this I’ve decided to stop iterating.
The key was the observation that if the brake cylinder is beside the hopper doors, the cylinder rod has to be beside them too. Otherwise, the cylinder has to be commensurately longer in order to drive the lever far enough to apply the brakes. By turning the B-end truck around (by shifting the dead lever guide), the B-end top rod lines up with the live lever on the truck. The A-end winds up looking more conventional.
Normally the hand brake rod pulls on the end of the cylinder live lever past the brake cylinder. This gives the brakeman additional leverage at the expense of more turns of the brake wheel. I considered hiring beefier brakemen, but decided it would be cheaper in the long run to introduce another lever at the end of the car. To keep this lever from fowling the rear wheel, though, it uses a rocker in pillow blocks.
Incidentally, after reading a description of the Pennsylvania Railroad’s GG hoppers, I’ve decided my hopper probably had flat ends, rather than a slope sheet all the way to the ends. This better explains the inside height measurement, and will also help my guys with shovels unload the car as there is now a flat place for them to stand!
This version of the frame is currently printing. I shall be very interesting to see what emerges in the morning!
Pembroke:87 
Such diligence. And the design looks so good.