She's an old one, most likely made in the late `70's. It might be the Torpedo .40 but may have some updated parts on it like the venturi. Usually there was linkage between the carb and exhaust butterfly, that's why I'm thinking it's been modded. The flywheel appears to be an Octura part but could be K&B.
The engine was popular in its time but now it's way outmoded. It probably went for around $100.00 when new if that as it was still considered a Sport engine at the time. It would be more for a collector so I couldn't even give you a ballpark figure.