I have a few other questions/comments.
What is your reason for selecting 6" wheels?
With the ground clearance, and lack of a "wedge" on the front and rear of the chassis, I don't see an advantage to a large wheel.
For a non-direct drive application, why choose the AM Supershifter over the
Gen I shifters?
The AM Supershifter contains an additional reduction but is otherwise the same internally. The output of the Gen I can be modified so that the sprockets are outside of the gearbox (see out drivetrain from 2011 or 2012).