actually, I believe I can be of some help...
The 3800 vin C engine would be an excellent choice to turbocharge because it shares a lot of design characteristics with the GN's 3.8 with the exception of heads and oiling system among the most important.
My suggestion to you would be to track down some rods and a crank from a 1992-1995 3800 SC engine for your swap. The SC shares the same crank as what you have but is balanced differently to compensate for the heavier, beefier connecting rods. I also believe that the intake you have now, which should be similar to the GN intake, would be better for turbochagring than the later vin L 3800 TPI engines.
When turbocharging this engine, you might run into a snag pertaining to the stock throttle-body-mounted MAF sensor -- as it may not work with boost. However, I see no reason why you couldn't run a GN computer on this engine. The 3800's DIS module differs from the GN's unit but it should still be compatible with the GN computer.
One other advantage of the 3800 vs the 3.8 turbo engine is that the 3800's heads have a better port design in stock form. Exhaust systems between the 3800 and 3.8 will NOT interchange. A big disadvantage with the 3800 series 1 engines is the fact that no one (that I know of) makes aftermarket cams for them. The stock one is a billet roller design but I have not heard of many being able to re-grind these easily.
Hope this info helps.