I would love to C some one going for Original Willys MB project. It is tough but not impossible. Getting all the parts together is really a trouble some project but for Jeep Lover it's worth it.
If U R interested in original then following are the Mechanical Specs for Original Willys MB:
Engine: L-Head 134 "Go Devil" 4 Cylinder in-line Water Cooled Side Valve,
Transmission: Warner Gear Model T-84-J 3 Speed synchromesh
Transfer case: Dana Spicer 18 2 speed
Axles=Spicer Dana 4.88:1 23-2 rear, Dana 25 front
Best of Luck