A shop here in town will do a turbo on a small block for $1500-$2000. They brag of a good horse power gain. Carb has to be re worked. I'm still considering the conversion after i get mine straighten out.
that seems awful cheap i think you would be better off calling the super charger store http://thesuperchargerstore.com/ look at this site its proven and lots of small block mopars good pictures in here also