I agree, the most reasonable thing to do, in all aspects, would be to replace the turbo by a new one, but, the supercharger seem so much more interesting.
Do you have any info about the amount of power this engine's internals can take? And the torque the gearbox can handle? Also, how far would i be able to take the engine's power without having to change parts of the fuel system? Since i'd have to remap, i could choose a size of supercharger to try to extract the maximum power output, keeping most stock parts as possible.