Dana 60 Bible:
http://www.pirate4x4.com/tech/billavista/60_front/
If the mods dont want the link here, take it out and just search web for "dana 60 bible" There are ratings from 4500 pounds to over 7000, so it depends on which one you get whether it may work or not. Same with the Cummins motor. A stock VE pump motor was 170 hp and 420 foot pounds of torque IIRC. The new ones are 400 hp and 800 pounds of torque. With some basic mods, any of them are power houses. The mechanical motors will run on almost anything and are simple to service and modify. After 07, they require ULSD.
A built ISB with accessories is closer to 1200 pounds. It is a long and tall motor, much more so than the Fuso engine it would replace. Add 360 pounds for an Allison automatic and another 150 pounds for an NV263 transfer case and you have a driveline that weighs 1700 pounds. A pair of D60 axles weighs in at over 1000 pounds. Probably not much different than the Fuso versions, but they are hard to find specs on.
Dana 60 gear ratios are plentiful, some as deep as 7.17 and as high as 3.73 (maybe higher, I am doing this from memory) There are tons of choices for axles, hubs, lockers, bolt patterns, widths, CV conversions, etc, etc, etc. You simply dont get that with a Fuso axle, at least not in the states.
300-400 hp should be plenty for a small cabover camper, tow rig, flat bed car hauler or about anything else you would want to do with it. The torque number for a 12 valve is about 2x, so if you have 400 hp, you are looking at 800-900 pounds of torque. Since it is a twisting force, you better build the rig properly to handle it.
Ian is not a "great" fabricator by any means. He does a lot of stuff wrong and for a show that "shows" people how to do things, I would not trust everything I saw on TV. Welding a T joint down hill is another one I just saw recently. Also thought it strange that he buys components to put the Ford axle in the rear and keep the leaf springs then cuts it all all for links and bags so he can lower the bed for a rock buggy to load up. Just throw some 4 foot ramps out and be done.
The truck is an NPR and there is not much room in the cab. A newer cab or a crew cab would be preferable for traveling/towing, though I assume he is not driving this across country and its just a project for the show and something to use locally. That said kudos for doing something different. If they do another Jeep build, I am going to hang myself.