Several guys have done the Serpentine thing. There was a guy I want to think in Topeka that made a set of pulleys and was selling them but don't see the link I had to him here, might be on my laptop at home. I do have a bookmark to a thread about supercharger builds on the HAMB http://www.jalopyjournal.com/forum/showpost.php?p=3037464&postcount=36 where the guy talks about how he built his serpentine setup. See if that helps.
MONGO


Mongo's Garage
Vintage GM Truck's & Parts
https://mongosgarage.com