Probably in too late for the OP since he already said he'd pass, but there are a few things that can be done to increase the reliability of these engines.
First, remove the plastic "Turbo Power" cover if it's still on the engine. They hold heat in, which is what typically kills the PMDs (Pump Mounted Driver) on these things. Dead PMDs are the number one reliability issue with the 6.5l.
Then, get an extension cable and move the PMD off the injector pump to a spot with a little more airflow. Make sure there's good contact with the heat sink.
Or, for the ultimate in reliability, ditch the DS4 electronic injector pump and install a DB2 mechanical pump calibrated for the same power level (190hp @ 3300 IIRC.) This does away with all the engine electronics, and only requires an ignition-hot wire to energize the fuel shutoff solenoid. You'll need an 85-93 glow plug controller (or spring-loaded manual switch), because 94-up engines use the PCM to control the glow plugs. I'd go with a switch that energizes a relay, since the 85-93 controllers don't always stay on long enough to heat the AC60G glow plugs in cold weather. I'm guessing it has an automatic, which will be looking for signals from different engine sensors, so get a standalone computer for the tranny. Or you could swap in a manual and eliminate that potential problem as well. The automatics are pretty reliable, though, just avoid rocking back & forth to get unstuck.
An advantage of swapping to a mechanical injector pump is you'll have the ability to use more fuels. The electronic pump uses an optical sensor inside the pump to help with timing, and fuel opacity can mess it up or keep it from working. Fuels you can run in a mechanical pump include diesel, Jet-A, kerosene, home heating oil (the dye would screw up the optical sensor on the electronic pumps), waste engine oil mixed with diesel, or unleaded gasoline in a pinch (also bad for optical sensors), waste vegetable oil, etc.
Glow plugs haven't been an issue since the early 90s when the AC11G plugs appeared. Current plugs are AC60G and DO NOT burn out. I've had them lit up for hours at a time while testing for possible use in my old 7.3l Navistar diesel (not the T444E/PowerStroke) and there was no swelling or deformation of the tip. Even back in the old days when the AC9Gs were used, they rarely burned out when the first generation (82-84) glow plug controller was working properly. Problem was, it was somewhat common for them to get stuck "on" due to one of the 4 switches inside welding itself closed, which obviously led to the glow plugs being powered as well. It doesn't take much more than 30 seconds or so of continuous power for an AC9G to swell and burn out. They'll last thousands of 8-12 second cycles, though.
The 6.2l and 6.5l are simple and pretty durable & reliable. One of their biggest advantages is you don't have to drive them any differently than you would a gasoline engine. They have their quirks, but what doesn't? They're not medium truck engines like the Cummins or Navistars, but will still last a long time with minimal downtime if proper care is taken and you don't hot-rod them.