custom one speed gearbox vs. AM SuperShifter

For next year, I'm designing our drivetrain, and want to know whether or not I should invest my time into a custom one speed gearbox, or an AM SuperShifter instead. I want to run a west coast drive, but I'm unsure if the supershifters will work on that.

It'll be our first time doing both, so I want some more veteran advice before choosing anything.

Thanks!