This was part of late 50’s Paxton VR58 Supercharger kit sold for late 50’s Corvette. The wide belt lower pulley is 3 Bolt. The Idler pulley is wide groove as well. The bonnet appears to be a vintage handmade and welded piece. The value is probably in the pulleys and idler for someone wanting to adapt a vintage Paxton or McCulloch on a vintage SBC hot rod.