I would go with the turbo unit off a G.M. 3.8 motor, since it is fairly close in size to the 4.0, and you can find the motors as carbed, no computer. I found an 83 Buick century WAGON with this setup. I am going to rebuild the turbo, or maybe use it as a core trade-in, since it is showing signs of oil contamination.
As for the S-charger, yeah, you get less hassle, less heat, AND less power for the trouble, since the 'charger is spun off the engine crankshaft, not exhaust driven like a turbo.