Hi Bug
There have been a couple of Jeeps done with a 6.5 that have been members here.
You can use any of the motors you listed,just depends on your mechanical ability.The easist will be the 6.2 or 6.5 with a mechanical injection pump.The cummins will be harder to fit into the engin compartment.The duramax requires computers that will have to be intergrated into the jeeps wiring system.And the power stroke is a little bigger than the 6.2/6.5 and will have a computer to run it as well.
6.2/6.5 parts are cheeper than the rest.I would look for a 93 GM pickup it was the last year with a mechanical pump and had the 6.5 with a turbo.Buy a complete running truck is the best,use what you need and sell the rest for parts and you could get your money back.
Thomas
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews