Thanks everybody for the feedback.
Power:
I expect there to be a big difference in power but I'm not too concerned about that. I'm currently running a Rochester 2bbl carburetor on my 454 and I never seem to need more than half throttle. The type of performance I really enjoy from the 454 is the brute low end. My primary truck chore is gathering firewood and sometimes the trees drop in such a way that they get really stuck. Whats left of the branches stick themselves down into the dirt and sometimes the tree will fall between other trees that pinch it. When I choke onto it and hook the other end of the cable to the truck I really enjoy just letting the big block idle in 1st gear low range and hearing the cracking and popping as the tree gets ripped out of its stronghold and slowly slides up to the road. My understanding is that the diesels will offer this same kind of low end torque. My concern with the diesel being under powered is that I will be consistently pulling too much power from the diesel on the road and cause premature failure. That's what I'm primarily wondering about when I ask "is the 6.2 a good engine for my crew cab?"
Economy:
My most recent tank of gas worked out to 11.8mpg. I think this is pretty good for a relatively heavy non OD big block powered truck. I'm not expecting the 6.2 to double my mileage, but I do think it would do somewhat better. In my mind the real savings, and the possibility of using the truck as a daily driver, comes from burning waste fuels that I can get for free or very cheap. I know many people will feel this is a bad idea, and I don't want this thread to turn into an argument about why burning ATF will destroy engines... we'll have that thread later. I'm still researching waste fuels.
I guess my primary question in this thread is can I expect reliable service from a 6.2L diesel swap in my 1988 crew cab? It doesn't matter how much money I save on fuel if the crank snaps at the end of the day on the back side of Spades Mountain.
I'm encouraged to hear that Yukon6.2 and Sctrailrider are having good success and what sounds to me like great economy without overdrives. And I do like the idea of adding a turbo and related manifolds from a 6.5, but I don't think I'd want to turn the fuel up. Does this effect reliability?
By the way if anybody's interested, swapping from 245/75r16 tires to 36x12.5r16.5 tires gave me an increase from 11.1 to 11.8mpg based on the first tank of gas. I didn't have to lift the truck (one ton frames are already a little taller), only needed to trim the lip at the very back inside the front fender well. I may still choose to lift it.