Rick,
The 6.2 I've got is in pretty good shape. With new injectors, injector pump, timing gears and a turbo, I would say it is comparable to a gas 350. Seems like suffient power to me. Not as torquey as a bigblock, but it gets the job done. Actually I prefer the 6.2 over the 6.5. I believe it has a shorter stroke and it holds up to extreme high rpm better then the 6.5.
Just my opinion.
Rollie