I would think long and hard about installing a turbo on a 6.2
Yes, Gale Banks sold a kit back in the day; yet others have taken turbos off of 6.5, installing them on the 6.2 and a few have fabricated a homemade manifold to mount a turbo to the 6.2.
Here a few points to consider:
It seems that there was a skirt coating on the 6.5's pistons that the 6.2 pistons did not have.
The idea was that the 6.5 pistons would see turbo service and needed to be able to withstand the higher temps and pressures.
It was suggested to use the 6.5 pistons in the 6.2 block.
I do not have all the details and I will try to search for some more answers and better information.
Next, the 6.5 have under the piston oil squirters to keep the piston cool.
The 6.2 does not.
I would seek out one the many surplus 6.5 motors coming out of military service.
Look for one of these later 6.5 motors where the block was cast by Navistar.
The easiest way to determine is the Navistar diamond logo cast in the lifter valley and other places.
These are the best of the best as far a 6.5 motors go.
These are naturally aspirated, so find a tired or broken GM 6.5, havert the turbo and rated parts, perform some upgrades, larger injectors, tweaked DB2 injector pump, etc..
This would make an awesome Diesel engine for a FSJ
Research more on TheDieselPage's forum:
http://www.thedieselpageforums.com/tdpforum/