That was my first thought but looking closer, it could be one of the Echo or other conversions done by the guy in MN that sold engines some years back. Can't remember the company name though. That split case below the mount lugs tells a story. Their 46 looked very much like this engine and they had several other different sized engines. Not sure if this is it or not but this might give you some direction to explore.

Edit: Memory finally worked: Company name was Brilelli.