Alrighty man, weird stuff. You must have Alzheimer's because you've made a thread on this topic already:
Next time I'd bump my original thread instead of making a new one if I were you. Anyways, here is a copy/paste of my last reply in your last thread, some good resources in there.
This article here should give you a really good idea of what it would take to build one:
Was written by Logan Imlach. His NS profile, I'm sure he'd be down to help ya out with a few questions (Sorry for putting you on the spot Logan)
Good luck man. Post pics if you make it!
And to answer this threads questions.
1. A centrifugal clutch would probably work best.
2. A 1" axle is way easier to find pillow blocks, gears, and other hardware and parts for as opposed to a 3/4" shaft. It's also stronger and that never hurts.
secret fucking SNOWBALL mission...
Chaitea, "The best gloves are mittens."
Park Guy, "Everytime it snows my dick takes a beating."