Coarse wood chipper/chunker, manual operation convertable to motorized

Am wanting to design a chipper that will handle up to 6" limbs and create 1/2" to 1" slices. It will need quite a bit of mechanical advantage, lever arm or pully system am thinking. Could be guillotine like or more rotationally based. Not sure what could do the job. Commercial ones are just so bloody expensive.

Familiar with that, too far from manual and have no tractor PTO to run it.

How about this?