If you expect to make any real power just by adding a turbo you are wasting your time.
More air requires more fuel, witch leaves you 2 options, 1 you can get pt-injectors with larger metering ports or 2 you can do a double fuel lime mod and turn up the pressure in the pump. Option 2 is the cheapest by far and only requires a few hours of your time. Option 1 is hard to find and requires you to take the rocker boxes off to install the injectors and then re set the injectors and valves. Almost all the 855 series Cummins parts will interchange with each other. As far as getting the motors to last, as long as you do your PM’s and watch your egt's they should last longer than you can drive them.